Hey, I have a 1989 Pontiac Trans-Am GTA with the 5.0L V-8 engine and its got about 200,000 kms on the engine so not too bad for the age. All I've done engine-wise since I recently got it was spark plugs, lead wires, dist cap/rotor, and a good cleaning. It starts up well and idles for a few seconds then rises up to 2k RPM if I don't touch the pedal? Strange thing is, if I start it up and flutter the pedal every couple seconds, it will return to idle at 1k RPM or less. But if I just don't touch the pedal it jumps to 2k RPM until I shut off the vehicle and restart it again, where the same issue occurs. Maybe a bad sensor? The charcoal canister is missing too but it doesn't seem like that'd be the issue. Maybe a problem with the intake? I'm only 16 and I'd love to get the car road worthy before the winter so i could drive it when i get my license in November. All help is greatly appreciated. Thanks!

 

check your idle air control valve and throttle position sensor... and put the canister back as well can affect fuel pressure

 

Ok I will check those thanks! I don't have the canister otherwise I would but I'll see how to properly bypass it so it won't affect performance. I'll share my results tomorrow

 

Plug off the missing canister hoses, the one that goes to the engine could be causing a vacuum leak.
Remove the tbi unit & clean the throttle blades. The base gasket on those loke to go bad too.

 

Ok I've already cleaned the tbi unit with some cleaner but maybe the base gasket is just bad.. there's a lot of loose lines from the previous owner tearing it apart but what stumps me is that it runs fine when its first started but as soon as you let off the gas about 4 seconds after it'll jump back to 2k rpm its weird