I have a 1987 Trans Am with a 305 TPI. Starting the car everything is normal, but once I press the brakes and put the car in reverse the rpm's drop below 500 and the car sputters. After I put the car in drive it drives normal for about 2 minutes then idles really high (1500-3000) and feels like its speeding out of my control. The car is hard to stop as well once the rpms shoot up this high. Any thoughts on what it might be? I have tried lubing the throttle linkage and re-adjusting the TV cable.

 

The reason its hard to stop is because with a idle that high the car is still trying to propel its forward. Same goes for the "speeding out of control". The first thing i would do is check for vacuum leaks

 

Is it the accelerator pedal sticking? I had this problem once on my tpi car. It was the butterfly assembly on the throttle body. I think it was a bad bearing indside it. Anyhow, i went to the hardware store and bought a spring to use as a return spring. Or you can replace the throttle body. So is it the pedal sticking?

 

Can you tap the throttle and the engine will return to normal idle?
If so,then as stated above , the TB is worn and the butterflies are sticking open

 

Yes I realized that is the reason it is hard to stop, the car will actually reach 40 mph without me even touching the pedal, and no the pedal does not stick at all. The butterfly assembly does stick open. Should I replace the whole assembly? or just try to fix the spring? If I manually shut the butterflies and the engines idles normal

 

there is no spring to fix. Replace the throttle body

 

I have this problem. I hit the throttle blade shaft with a drop or two of motor oil (telescopic nozzle) twice a year and its fine. Fortunately, mines a manual, so i can quick hit the clutch if i don't oil in time. I will get the throttle body rebuilt or buy a new one, once i know what direction i want to go with the engine.

 

I had one act like that but it just needed the butterflies and the throttle body bores cleaned. Too much gunk on them and in the plenum from excess blow by. A can of carb cleaner on the butterflies did the trick. No more sticking.

The IAC motor & passageways were really clogged too. It needed a thorough cleaning as well. Worth a shot before you go replacing your throttle body or having it rebuilt.