What are the signs and symptoms of the TPS going bad. My car is a 88 GL10 AWD turbo. It has an idle speed that doesnt usually go below 1000rpm and now, when you rev it up, and the engine comes to an idle, there is a funny vibration.

you can check it if you have a good DVOM.

 

there is also the closed throttle switch built into the tps.(the flat connector)

 

TPS has the round connector.

 

back probe on the signal wire (green I think it was) and with the key on verry slowly open thew throttle and look for a smooth voltage transition. don't bother with the ohms BS. checking voltage will tell you more.