I own a 1991 Oldsmobile Cutlass Cruiser S. The car idles fine, starts right up. No problems at top speed. But, after the car warms up I have acceleration problems. When I come to a stop after driving for about 10 minutes. I can apply only very light pressure to the gas pedal, and sometime not even that or it will backfire and stall. The backfire is not in the tailpipe but in the Throttle Body. I jumped the ALDL and got the code 25. Which is the MAT sensor signal is too high. I replaced the MAT sensor. No change. I reset the ECM and ran the car. When cold it's fine, same problem when it warms up.
I DO have a crack in the exhust manifold, right at the split before the O2 sensor. I replaced the fuel filter and capped off the EGR. I checked all the vacuum lines. Seem to be fine.
OH, I replaced the air filter and one day later checked it. The outside is clean. The inside is already sooty and brownish.