Good afternoon. I have a 1997 5.7L vortec in my Jeep. When it is sitting in park the engine runs great. I can push the accelerator down and revs up like a champ. Sounds great and does not sound like its missing at all. However when driving (5 speed manual) it feels like its missing. It will accelerate but is running rough as heck. No codes are being thrown by the computer.
Fuel pressure is 63 psi at start up and 56 psi while running and like I said, in neutral it has no problem hitting hi rpm smoothly. EGR system has been removed an deprogrammed from the PCM. Rear O2 sensors the same. What are the likly causes? MAP? Throttle Pos sensor? Any help is appreciated!
Terry