1FasMax

When I start the car when its cold....it almsot stalls out and then goes to a "normal" idle of 750 rpm......as if its already warmed up....I know that when the engine is cold that it should idle higher for a couple minutes....like at 1500rpm, and slowly drop to a normal idle as the car warms up....any idea what I should check to correct this problem.....lately I have just been holding the pedal down a little to make it idle at 1500rpm until it warms up....P.S I changes the Coolant temp. sensor....whereas I thot this might have been the cause....Ive been told that is the only sensor that knows if the car is warm or cold....