I have a 1993 Lexus SC400. My car has been idling high then low while driving, when i came to a complete stop today it idled low then shut off. whenever I'm at a complete stop it idles low then acts like it wants to shut off, but when i turn my air conditioner on it doesn't idle low and act like it wants to shut off. What could cause this problem?
This is a classic symptom of an IAC ( Idle air control) the reason it seems better when you turn the AC on is it cranks up the IAC even more to help it idle. You should have the IAC replaced and the throttle body cleaned inside at the butterfly as it gets clogged or gummed up and restricts airflow at idle.