try your tps sensor . means throttle position . may be giving a false reading. /
e.g.r. valve replacement fixed mine. symptoms where rough idle and "surged".
There really isn't an adjustment just the IAC valve which may be dirty causing the idle to be too high or too low so the Idle Air Control valve has to be cleaned or changed.
You may have leak in the intake
buy a toyota !! Problem solved
There are a few things that could cause an 87 Chevy Astro to idle high when it is started and warmed up. It could be a bad fuse, a leak in the vacuum, or an issue with the throttle.
you most likely have a horrible fuel sensory causing your car to be bad at idling. also you may hvae reved your engine to hard and that is causing it to idle.
it maybe out of timing or the valve seat is leacking use a compression tester to find out if is the valve leak
Is anyone on line to help me with this question? Where is the fast idle thermal valve in a 1997 Chevy astro van located?
Bad egr valve or a gummed up throttle plate or a bad idle speed motor,also check forbroken hoses causing a vacuum leak
need more info but just guessing here vacuum leak causing high idle and dieseling cause by high fuel air mix why it will not shut off
have lost my idle on a 1995 mitsubishi--what is the problem
vacuum leak, bad idle control sensor