I own a 1998 Rodeo with a 3.2 L engine. Car starts and idles fine, when I start driving it , within just a few miles it starts to "bog down" when I try to accelerate. Almost like the timing is temporarily retarded. Once past a certain point on pressing down the accelerator petal it jackrabbits back to life. This issue is completely intermittent, as it will do this for a while ....then it stops and the car runs fine....then it will start back up again. I am an experienced home mechanic with over 4o years experience , but I've got to say this one has me stumped. I have.....
replaced the fuel pump, fuel filter, throttle positioning sensor, coil packs and plug wires, plugs, timing belt, pcv valve. I have checked the EGR (good), MAF sensor, IAC...all functioning. I have had the car put on the computer and checked to make sure that the oxygen sensors are all good and that the wiring didn't get crossed. Catalytic converters are in good shape and not restricted. I get no other OBD11 codes but the "multiple misfires" code. Computer diagnostic leans toward passenger side bank on misfires....but this diagnosis also is not consistent.
The fact that it is intermittent leads me to believe this is an electrical/sensor problem...and not a timing/fuel/compression/headgasket issue. Compression checks excellent and consistent across all 6 cylinders. Fuel pressure at the rail is good. Could this be an ECM issue, and if so why would it not throw different fault codes??? Any advice suggestions would be greatly appreciated