I know this sounds like an obvious question, but.....my car started staying at a high idle off and on. I looked at the throttle position and saw that it had around 1/16" gap when the idle was high. A light nudge and it returned to the correct position. Wiped the accelerator cable and added a light cable oil. The cable doesn't feel overly tight, but I still have the throttle position problem. A slight wiggle of the cable and the plate rotates to the correct position. I am not completely conviced that the cable is causing this. Anyone else had the same situation? I can only recreate the problem with the car on.
92' Z28 With 5.7 TPI

 

sounds like you have carbon build up behind the throttle plates, this happens to a lot of cars. you can clean it while it is on the car with a small brush a throttle body cleaner but, If it were mine I would just take it off and clean it real good from the back side. remember to get it very very clean or it will stick just like you did nothing at all.

 

Thanks for the idea! I decided to change the throttle cable since it had a small area that was starting to fray where it rides on the throttle wheel. Boy did i get a suprise! the cable was completely rusted through right at the firewall. The inner cable was actually exposed. You could not see it because of the insulation tube over the cable. I think this was the cause of the problem, but if it isn't i will be cleaning the throttle plates. The cable was only $16 with tax at the dealer! Forty five minutes to install. I don't know how common this rusting is, but it could sure ruin your day if it decided to get stuck open at full throttle.:lala: