I am totally frustrated over this strange idling. I have a 85se. Once in a while(mostly when the engine is warm), the idle will jump to around 1000-1100 in neutral(at a stop sign, etc.) instead of the regular 850. I found that if I put it into first gear and slowing let clutch out without putting on the gas, the idle will immediately drop back down to normal at 850. The car is all stock except for the RB streetport exhaust. What gives??

 

I don't know if this will help, but My cars idle would hang at 1100 or so sometimes and it was due to the cruise control cable getting stuck.

 

My SE use to do the same thing, I think I traced it down to the throttle plates not closing all the way because the throttle return spring was not strong enough to close them all the way. I made cut the spring a little shorter and reattached it and that cured the problem. Also, I'd check to make sure your dashpot is adjusted correctly, and lube up the throttle plate shafts while i'm there. After all this, you might want to check your TPS to make sure it's adjusted right. Take care.
Matt

 

Thanks for the tips. I will try to look into it this weekend. I will post results.

Jeff