Well about 5k miles after i got my new to me F150 the truck started missfiring and shaking REALLY BAD when i got on the gas really hard but it was an occasional thing...in the past few months it got more and more frequent. It was throwing the code for missfire in cylinder 8. Well here lately every time i'd drive the truck even just regular speeds it would start vibrating a little from a slight missfire...well shortly after that it began getting to the point where it would take a ton of gas and a ton of rpms to get the truck up to speed. Took it to the shop and low and behold 4k miles before the warranty expired we find out my fuel filter was EXTREMELY clogged causing lack of fuel to the rear cylinders which in turn ruined my cat from running like this for so long. Anyways i am about to go pick up the truck and this will be the first time it will drive like a 5.4 is meant to since i never got on it hard the first few months of owning it.

 

Dude that's awesome you caught that before it expired...I'd get the plugs changed too

 

I wouldn't think a clogged fuel filter would be covered by warranty.

 

Fuel Filter wasnt....catalytic was, but the fuel filter only cost $75