I have a '91 F-150 w/ 4.9L(300) Mazda 5 speed. Idles fine for the most part she runs fine. Difficult when starting, about 4 tries till go.
New plugs, wires, cap, rotor, TFI, coil, tps, IAC, EGR, MAP, clutch, starter, alternator, and battery.
When sitting still and depressing the excelerator pedal, it will rev just fine to say 3500-4000. The problem starts as I'm driving, when excelerating to shift around 2500-3000 rpm it will "chuck and buck violently". It does this through all the gears. Then when cruising its sort of ok, but when I let off the pedal, it wants "chuck and buck again".
Please tell me someone else has experienced this and knows the cure.

 

Sounds to me like might be a timing thing. Try unplugging your SPOUT connector and see what happens. You will lose power cause your timing will be 10 BTDC at all RPM, but maybe it will help diagnose. Then put that back in and then unplug the knock sensor. It's on the side of the block under the the distributor and coil. Then drive around again. Good luck.

 

Thanks sounds possible, I'll try this and let you know. Appreciate the help.