I have a 2007 f-150 with a 5.4 V8. A few months ago, it started missing real bad so i replaced the plugs and rubber boots. This seemed to fix my problem; until a few days ago when it started again. The first time it threw a code for cylinder 1, so i swapped the COPs from 1 and 2. It ran good for a few miles, then again, threw a code for cylinder 1. Later that day it also threw a code for cylinder 3. Since then i have not had any more codes pop up but it has a periodic miss and idles rough. It also seems to get worse after it warms up. Should i go ahead and replace all the coils or is there something else i should check out? Thanks for any help!!

 

Possibly a bad fuel injector.

 

That was another thing I was suspecting, gonna replace the fuel filter tonight and swap out the 1 injector out with another.

 

How many miles are on your truck?
Just a thought, try filling your gas tank up and add a can of SEAFOAM to the fuel and run it out, this will clean your injectors and may solve your problem without pulling the injectors, as for the fuel filter replace it.........it's a PITA but it's do-able, search here for how to do it, it will keep you from getting gas all over you!
One other thing, I'm not telling you to do this so use your own judgement here, the gas cap on my truck says use BP gas(reg.) so I started using BP gas, my mileage as gone up and my truck runs without a rough idle and runs very smooth, I don't know for sure if it does because of this or not but some clam it does and I have to agree!

 

It has 128,000 on it and I put seafoam in it a couple days ago but doesnt seem to be helping after about a half a tank. I have never changed the fuel filter on it so im thinking that may be part of my problem. As for the BP gas next time i fill it up i will give that a try and see how it does.

 

Well got the new filter on and swapped the injestors so we will see what happens now. Still idling real bad so guess the filter wasn't the problem.

 

I would remove and clean the MAF and throttle body. Easy to do, free, and can cause a rough idle.

Also how do you know it's still not a bad injector? Just by swapping you may have moved the issue from one cylinder to the next.

 

Thats what i am hoping for, if the problem moves with the injector then i will know. Will try cleaning the throttle boby and MAF this weekend and see what happens.