I have a 1990 Iroc Conv. with 5.0 and auto trans. The car when I bought it started and ran great. Drove it with dealer plates 60 miles home and the car started acting up. Foot to the floor no power. I was able to get the car home feathering the gas pedal to keep it running. It does not stall. You press the gas and it sounds like it's going to stall and when you come off the gas it idles fine. The car sat for 4 years before I bought it. I have changed the fuel filter, cap, rotor and tested the cars sensors with a scanner throught the OBD port. All of the sensors are working fine, the computer is able to get into open and closed loop. The map sensor, throttle position sensor and temp. sensor are all working fine. My buddy thinks the computer may still be in limp mode. Any help would be appreciated.

 

did you check the fuel pressure? Might be a bad fuel pump....or plugged if it sat for that long. Also could be bad gas.

 

I checked the fuel pressure at the rail it was 42 lbs. at idle and 40-45 when it was running. I'm going to drain the gas this weekend. I added 6 gallons of 93 octane and put in fuel injector cleaner when the problem started on the way home. I thought it was bad gas also.

 

I would also suspect a fueling problem. The fuel pressure at idle might be fine but what about under load? Can you see the gauge from the driver seat? Or can somebody watch the gauge (standing on the SIDE of the car) while you put it in gear and try to load the engine while applying brakes? As tenpin842 mentioned, it could be a plugged fuel filter or the fuel pump "sock" (it's a pre-filter).

Let us know what you find out.
Lou

 

When I checked the fuel pressure under load it dropped at first about a pound then increased a few pounds when the idle increased. I'm still hoping it's just bad gas. I need to clear the computer. I heard if I disconnect the battery for 10 minutes it should do the trick.