1997 Cavalier LS - Automatic Transmission ( < 150,000 mi)

Getting my car back from my parents after loaning it to them when they needed a vehicle. It's been in and out of the shop for the last several months and they have replaced spark plugs and TPS. Diagnostic shows no errors and cat and fuel pump both checked out OK. Before this, the only other problem was the water pump which I replaced about 30K miles ago. No electrical problems. Car starts up with no problems and idles smooth. Shifts into gear smoothly and drives forward and backwards.

Now here's the problem:

Push down on the gas and the car won't go above 1500 RPM and doesn't hit more than 5 MPH in any gear.

Any thoughts? :confused:

I know you said the cat checked out OK, but from what all you described, fuel pressure good, transmission and idle etc, it sure sounds like it could be an exhuast restriction. Does the accelerator cable open the throttle fully? I know that's unlikely to be it.

Also check the MAP sensor, and more importantly the vacuum source for the sensor.