Hello, first post!

I purchased a 2017 F-150 3.5 eco boots last year with 65,000 miles on it. It ran great for 2 months. Then it started misfiring when heavily accelerating (to pass someone, or going up mountains). A friend of mine who used to manage a Ford Service Dept recommended I treat the engine with 44k, but that didn't solve anything. The check engine light did eventually come on and displayed P0303 and P0306. After looking online for solutions, I discovered 2 spark plugs that appeared to be faulty. I went ahead and just replaced all 6 plugs and respective coils with parts from OReilly. That seemed to have fixed the problem for about 2 weeks, then the same problem resurfaced. I have just kind of dealt with the misfires and driven it carefully. The other day I was driving it, the problem has gotten worse, Upon accelerating, the truck will shake like crazy, and the check engine light will just blink and I cannot pull any codes off it. But if I drive it hard, really hard, I can get the check engine light to stay and and pull off the respective codes (P0304) - which was a cylinder 4 misfire. I swapped both the coil and plug in cylinder 4 with cylinder 5 and got the problem to follow the swap. I took the coil in and got it replaced but that didn't solve my problem.

Another side note, I can drive the truck at speeds up to 80 or even 90 and it will perform perfectly.

Any other advice you could share would be greatly appreciated.

Tim

 

We have an idea of which cyls are involved, but we need some addl info.
Need a capable scan tool to provide data stream info.
With that addl info, should have a better idea of what is going on.
Throwing parts at it can get expensive and disappointing.

 

If you get the misfire code, usually there is something to do with your coil and plugs, but not always, especially when you get multiple misfires randomly.
You said you already replaced all 6 COPs and the plugs then you should start looking at something else related to air and fuel.
The easiest, without any tool needed, is to remove your MAP (not TMAP if you have 2 MAP sensors) sensor's electrical connector. Next time while driving when the truck is shaking, pull over to a safe spot and shut off the engine, key out, pop the hood and remove the electrical connector of your MAP sensor, then start up your truck and continue your trip. When you drive with your MAF or MAP unplugged, you will get a CEL, but it will go away later when you plug it back in, your truck might be in LIMP mode, but you will likely get rough idling but not shaking/sputtering/stalling anymore, your PCM will use a factory predefined air fuel trim, if your truck runs a lot better, that's a good sign that your MAP is at fault. Before buying a new one, try to clean the electrical connector first using contact cleaner, and use wire brush if needed. Don't need to clean your MAP with MAF cleaner when it goes bad it's too late to rescue it.
Other things you can do, but not as easy as the MAP above, is to remove just the electrical connector of your ECT (Engine Coolant Temperature) sensor and use contact cleaner to clean. If you never replaced your fuel filter and PCV valve since you took over the truck last year, now is the time to throw this kind of parts at your truck.
Seriously you need more than just a generic obd scanner if you decide to fix this yourself.