I have an f150 that I have done everything that I know to do and still no results. It vibrates very bad abd runs very rough below 3000 rpm. I have replaced The fuel pump, spark plugs, wires, checked the timing, cam sensors, coil packs and a new computer. I am at a loss. Does anyone know whats next? The dealership diagnosis was out of time but its not. Please help with any ideas.

 

What year?

 

How do you know for sure? Have you done a compression and leakdown test? Any CEL and/or codes? What year?

 

check your harmonic balancer

 

now that you've thrown a bunch of money at the truck lets start where you needed to in the first place...


#1 have the codes read
#2 what plugs, plug wires and coil packs did you use? (also who swapped the ignition system or motor? since the 5.4's never had coil pack, or plug wires you're truck either isn't stock or you hosed on repairs thus far)
#3 why did you change the ECM?