my friends car has been acting up lately. whenever he starts the car up after it has been sitting for a bit, it will idle from 1500rpms and the drop to 500rpms and then back up to 1500rpms. it will do this until the car gets to running temperature. it also likes to die if its either too cold or if he revs it too high and then pushes the clutch in while he is braking. anybody know whats up?

 

YEAH IT SOUNDS LIKE IT CAN BE FAST IDLE PROBLEM. WHAT YEAR AND MODEL

 

check the IAC control. it stands for idle air control. or check the throttle position sensor. its one of those 2. or if hes done a new manifold or something or put a new throttle body on sometimes thats messies with the idle