I was having some problems with the idle sticking when I pushed in the clutch. This was caused by the throttle plate/linkage binding. I still have a problem (slight) when the engine is warmed up and after driving for 1/2 hour or so that the idle will still stay high and then gradually drift back down to 750-800. Here's a graph from my scanner. As you can see the Throttle Sens (red) immediately drops back to 0.56 when the clutch is in; the rpm's drop initially with the throttle sens but spike back up because the IAC decay is not as great as the throttle; then the rpms gradually come back down as the IAC closes. Is this normal?



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1988 IROC-Z
5-speed (was 7R4)
Edelbrock TES

 

I have had an idle problem like that as well. Clutch in and the idle just won't come down.

After checking the return on the throttle and adding a larger return spring, it helped a little.

The thing that fixed it for me was replacing the throttle body gasket. I think it was letting air in somehow?? anyway is was fully trashed so I replaced it.

This seemed to fix my problem. Maybe it will fix yours?