Injectors?

Maybe a week ago I starting noticing some bucking issues while driving and a little bit of power loss. I checked my OBT and saw my air:fuel ratio was slightly lower than it should be. I’ve considered upgrading my injectors but never heard anyone say much about what CC is best for different set-ups. Anybody here upgrade their injectors and if so what brand and CC’s do you run?

By A/F ratio being “lower”you mean lean?
If you didn’t have a problem before, was there anything that you changed just prior to the problem happening?
You might want to have a look at the connections and harness to the injectors.
I don’t know how many miles are on the car, but I will assume over 50k. If you can’t make the issue go away by double checking the harness to injectors. You might want to pull the oil dipstick and check out the oil condition and smell. Is the oil smelling like gasoline? Is the oil level above the max mark on the stick?
If so, you might have a leaking injector or two.
I would have the injectors cleaned and flow tested by a firm that specializes in fuel injectors like Marren. They are located near Oxford, Connecticut. They will clean each one and then put it on a test bench and verify the functionality and flow. (www.injector.com)
I had them service the injectors on my brothers Mustang several years ago. All they do is fuel injection and fuel injection components and service.
You can get two injectors serviced for about the price of one new injector.
After they are done each injector will have a report and a graph of the original condition and the serviced condition. Then you will know what you are working with.
But, again. I would be looking very closely at the connections and harness first. If you have made some changes or pulled things apart on the intake system.verify that everything is tight and right before you start on other things.

A bucking issue may also mean several different things; including timing and poor electrical.

You own a 2014, that means aged nearly 9 years... has the timing belt, water pump - Alternator, even the battery post to frame connections been checked and are in good condition?

Spark plugs?

So if the main serpentine belt has been replaced, do you notice any other quirks? Like, at a stoplight, do lights dim when at idle, then brighten considerably when you start to move? Find that your Music USB seems to reset often like back to Track 1? Fan and AC works, but sometimes seem more anemic than what they used to be?

These can just be a sign of a weak battery, or some simple corrosion to the electrical system, making the communications to and from various systems - more noisier than what they were.

I see this often in my own cars, even the Ford.

So I get after the ground bonding points and loosen, then reseat them - tight. Double check the posts on the battery, and if I find - say the AC fan, slows at idle but revs (spins up) faster at a slightly higher off idle speed (manual clutch) with that idle up you can feel when you are stopped and clutch in - brake off, that idle-up to help with takeoff.

Seems corrosion and the like, being this car is more electrical - can affect handling and performance.

Electrical power demands affect performance and can also be affected by electrical loading too, like steering wheel seems to need more effort in turns at lower speeds than what you are used to, or when at a stoplight making a turn - it pulsates - that too, is a sign of a weak battery - especially when the lights are on, it's winter, and you're running the Climate Blower at full speed in wet - snowy conditions, just trying to clear the front windshield.

That hesitation can mean many things...
I wouldn't blame injectors unless they've already been tampered with - then it just might trace back to those "O-ring" seals. They can easily crumble when you use various blends of fuel - Avgas or fuels with 15% or more Ethanol - that being 9 years old and if not recently serviced - can change A/F ratios from their sealing effort is giving up.

PCV valve and EVAP can not be ruled out either...

But when A/F fuel ratios seems "low" - can mean two different ways to look at the condition; one being a stinky exhaust - that usually means rich (carbon soot around the exhaust pipe), or lean condition also brings up engine noise and hard knocks or tappet noises while trying to accelerate - starving the cylinders and the fuel that lubricates the valve seat, is not there to help keep the seat clear and free of carbon - instead its running dry - making valve train noise..

Which type of event are you having?

After checking the things you mentioned I’m happy to say all my harness connections are solid and nothing shows any signs of deterioration or abnormal wear. I also recently did an engine tear down because I feared I bent a vale during handful of aggressive and hard pulls about a month ago, and I saw no internal signs of damage, scorching, or anything else that would lead me to believe that the engine leaning out is caused by anything other than my engine is consuming fuel faster than the system itself is feeding. I did maybe an hour of research after posting my original thread and found maybe four good upgrades for injectors and was hoping to come back to this and find that someone had maybe already upgraded to one of two and had some opinions to weigh in with. I’ll go ahead and upgrade the injectors as precaution since I already expected I’d run lean”ish” after swapping both manifolds.

Let us know how it goes.

Being a fleet driver, I can already attest that not all injector mods are worth their salts.

In fact, they can make the MPG crash due to the amount of fuel they're capable of pushing into the cylinder and the results you get back out of it are two different things.

Automatic and a power mod give you only so much - the Manual might give you a little more but the overall end result is more of a need to make oil changes and fuel stops to make it thru the years you own it.

If you race - that is one thing, but if you commute or work as some sort of UBER - Dash or Taxi - the cost of fuel to keep it running gets pretty stiff on the wallet and ledger sheets

Currently working in one now, that if the wind blows in the right direction - you can get the rich rotten egg smell from the catalytic converter trying to clean up the exhaust - just a reminder that it's running rich as you're stuck in stop-start traffic trying to make someone happy delivering what they need to make their stuff work right.

I'm in a position where I see the results of bad decisions of the behalf of previous owners - and see the relief from the current ones knowing it can get fixed right so they can have a car that works again.

So unless you have the $$$ to do the upgrade - you'll also need to do the tune, the upgrade alone usually is not worth it. The fuel trim the system attempts to make usually sets the MIL light as it's trying to tell you it doesn't like the new setup.

With the Fiesta no longer being made, it's a relic, so to just throw money and parts trying to get more from it is not worth the replacement cost. For you may not like the lengths, jumps and hoops you may have to go thru to get another car to mod.

You may not have wanted to hear that, but the Fossil fuel era is going away, people are also being led to believe that one is better than the other and the other side of that coin is saying the same thing for their side with the rejoinder that it takes longer to recharge than it takes to just fill up a tank and be on your way.

We're being forced into a direction - whether we like it or not. Until the up-front costs of owning up to their recommended upgrade to the family car, my approach is to preserve that which you have - until that time comes where the switchover - or our end times - is easier to accept the outcome.

Another thing you're going to find, is the level of mod tunes you can acheive is less in the later model years, so if you trash the 2014 - a 2018-2020 year mod is going to be harder to acheive - they locked up the PCM pretty tight - so you're also stuck with a range of years and the parts for them, you can possibly work with - Ford learns from their mistakes.

It's your choice in life, I learned hard lessons thru the years to preserve what I've invested in - it's not worth jumping ship or trying to make a canoe into a sailboat - one requires a strong swimmer and the other needs a keel to keep it upright - either way you'll need to add more in parts, labor and it's cost, to obtain it.

Don't worry, we're on your side, we get it. We just can't offer good solutions for mo' powah - power delivery options except to get rid of it and buy the Ferrari...

...You can not push start a Tesla, it'll take several miles of towing it on all its wheel to even charge it enough to (hopefully) make it to a place to plug it in....

UPDATE!!
I got the injectors and they’re perfect. My A/F ratio has returned to a more appropriate level and I’m no longer leaning out at higher speeds. I also took the time to get a better tune as to get the full effect of the injectors. I bumped the duty cycle up to 80:120 and HOLY S**T does this thing get moving.