I have a 1989 F-150 5.0L. It starts great, idles a little high at first then smoothes out, once you put it into drive and accelerate at a little past idle speed it starts shaking and hesitating once you floor it chuggs a little then runs great.

Changed fuel filter, PVC, TPS, Distributer cap, rotor button,

Any ideas???

Thanks

Keith

1st ford product in my life

 

It could be the routing of your plug wires. Keep the wires for cyl 7 & 8 seperate as they fire sequentially and are known to cause stumbling problems from induced voltages that result in misfiring.

It could also be running too lean. Verify this by looking at the plugs... they should be tan colored but my guess 1 or more of yours is white. If only 1 plug is white suspect a partially clogged injector. If all are white then suspect the O2 sensor or MAP sensor. Pull the codes for additional confirmation.

 

I would get a can of seafoam and pour it in the tank to clean those injectors out if that's the case.

It does sound like a lean condition, so my first thought is a weak fuel pump. A fuel pressure gauge is the only way to test it, though.

 

I pulled my plugs out today, the number 1 looked tan with alittle white, the last one on the driver side towards the firewall was faulty. The diode was offset from the thing on the top. I would say it is broke. Would my truck run right if the plug was like that?