Yes, if there is any vacuum leakage between the MAF and throttle body, engine would stall or idle badly.
When engine idling speed increases, it is usually due to excessive air getting to the intake manifold. There should be a vacuum leakage somewhere and usually a faoult with the IAC would not increase the rp to 4,000, A stuck open IAC woulod most likely increase the engine rpm to 2.5 k maximum.
Not likely to be the MAF as well as you require more air to get to the manifolds and since throttle plate is closed, it is not going to increase up to 4 k rpm.
A leak with the intake manifold would be more likely. Was the TPS calibrated correctly?
Using carb cleaner and spraying them around suspected leaking areas would mosty likey result in changes in the rpm if any leaks are present. Ensure the PCV is good.
Friday, September 16th, 2011 AT 1:16 PM