hey guys, i need some help adjusting the idle speed, i have a 1990 350, and right know its ideling at about 1200 rpm, it was at 1700 but i adjusted the idle speed screw today, and it resulted in 500 rpm in the right direction, however adjusting it any more dosent do anything, what else can i do to get my idle speed down to 400 rpm, " thats where it should be right?" i think with it ideling that high results in poor stoping distances and premature brake failure as well as lowered gas milleage, am i correct?

 

TPI? If vacuum leaks have been ruled out, and the Throttle blades are fully closed, may be an issue with the IAC valve being retracted.

 

Just a silly thought, but did you check to see if the throttle dial was closing completely against the screw? I know sounds like a smart a__ question. My car was doing the same thing on an intermittent basis. After checking everything out i unhooked my throttle cable to see if it moved freely. It wasn't too bad, but it was enough to just slightly hold the throttle open. I took out the old cable and found that it had rusted inside the casing near the firewall. Hope this helps.