2007 5.4 F-150 63,000 trouble free miles. Driving the other day engine started missing real bad on acceleration, couldnt get over 45 mph. Pulled over shut it off and restarted and ran better but still missed, engine light would flash when missing then stayed on solid.
Took to dealer they said oxygen sensor was bad and cats plugged. They replaced the cats under their extended warrenty
I picked up truck and it ran alot better until I stomped on it to pass. Whwn trans kicked down it missed bad then stops when it upshifts.
Every now and then it might just hesitate upon normal driving but not bad, never through a code
Took it back to dealer and they couldnt figure it out .
I am greatful they arent randomly replacing parts until they find whats bad but I do want it fixed.
Any ideas guys??

 

Have the plugs been changed yet?

 

What you described is usually plugs, bad fuel, dirty fuel filter or dirty throttle body.

 

this. run some good quality gas, then if no improvement change the fuel filter, then if no improvement do the plugs. this is just cheap/easy to more expensive. but i would say its plugs

 

Wouldnt it run bad at all speeds though ifit were the plugs?
Thanks

 

No it wouldnt

 

Typically, the plugs breakdown under acceleration.

 

Thank you for the replys ,one more bit of information.
From a dead stop under full acceleration it runs like a top , no hesitation/miss at all. It is only when cruising at speed and stomp accelerator that it misses/hesitates when downshifts then stops missing after it upshifts and continues to accelerate
Could this still be plugs?
Thanks guys

 

Yes it could. Ford recommends plug changes in the 5.4 3v every 60k.

Try running a couple bottles of Techron through the gas and change the fuel filter. Inspect the FPDM for corrosion.

 

OK,new plugs it is and I will check the FPDM, will let you know the outcome
Thanks again

 

possibly a coil issue, but you need to do plugs first.

they also should check fuel pressure to verify its not starving for fuel

 

Fuel pressure has to be read out with a scanner, and the FPDM controls it.

 

Has the fuel filter ever been changed? If not it is past due...