My wife has a 2001 ES300 with 90,000 miles. In the morning when she started it, it would stall. She would have to start it again and feed it gas to get it to rev at a higher rpm until it warmed up. Normally when you start the car when cold it automatically should rev at approximately 1500 rpm or so until warm and then reduce the idle rpm to around 500-700 rpm. My solution was to clean the IAC valve first. It was not that dirty. Do not pay a mechanic to do this, it is not a difficult operation to carry out. Result: no change! I called my mechanic and explained the problem. He mentioned it may be a dirty IAC valve. Told him I already cleaned it and asked him what the computer uses as an input to determine how much air the throttle body allows in to control idle speed. His answer was the coolant temperature sensor. I read on another site that if your coolant level is low than your coolant temp sensor will be unable to give an accurate reading to the computer. Makes sense to me. Even though there was fluid in the coolant overflow tank I took the car to Kwik Kar and had them flush the coolant system. This morning she started it up and it worked great...just like new.
