high idle up to 2000rpm when it's cold on 1999 Toyota Avalon

High idle up to 2000rpm when it's cold, after warm up for a few minute,engine run normal at 800rpm. I did replace cooling temperature sensor and idle air control valve but engine still runs high idle when it's cold.please give me some advice. thanks a lot.

by in Bel Air, MD on September 09, 2009
2 answers
ANSWER by , September 09, 2009
The idle air control (IAC) gave a lot of trouble causing the car to stall when started from cold. ( I usually clean them reassemble and they work for years later). I wonder if in the past someone altered the idle speed screw at the throttle butterfly housing, the screws normally have a dab of yellow paint on them. Look for signs of the screw having been adjusted. It should not have been, it can through off the throttle position switch adjustment and "base idle speed". There is an adjust procedure but the screw should not be touched generally. Ensure water passes through the two water hoses at the IAC valve both small diameter hoses should feel hot as the engine gets up to operating temperature.
ANSWER by , October 20, 2011
I'm having the same problem with my 1996 Avalon. Did the high idle problem every get resolved?