This is a problem that I've been fighting for 6 months. I've had the truck in the shop several time but no one can find the problem all they want to do is change parts hoping to solve the problem by accedent.
The truck is a 1987 Bronco II with a 2.9 v6, 4wd with auto trans. It starts and idles fine but when I reach about 45 and back off the accelerator it acts like it's starving for gas and starts bogging down. It then starts to backfire through the exhaust pipe. As soon as I give it some peddle it lines out until I back off the pedal and then the problem repeats. So far I've replaces both fuel pumps, fuel filter, brain, tps, temp and O2 sensors, pcv valves, plugs, plug wires, distributer cap and rotor, and had the timing checked. Does anyone have any sugestions as to what the problem may be? Check engine light has never come on and mechanic says it doesn't show any codes.

 

You can try the EEC and Fuel pump relay in the power distrubition box under the hood.

 

Also if you have high milage the distributor may be worn with too much play.[hr]Or the pick up in the distributor may be bad.[hr] If so it is easyer to replace the distributor.

 

Thanks 94 4x4 ranger both relays were replace at the same time as the fuel pumps. I'm not sure about the distributer wear but the mechanic said he checked it when we replaced the cap and rotor and it was ok.

 

Then it is probly the pick up.