Mitsubishi Repair: 03 galant, throttle position sensor, vacuum leaks

Question
i have a 03 galant. when i start it it will idle at 500 rpm and alot of the time it will surge up to 2000-3000 rpm, what do you think this is? talked to a few mechanics and they all say something different. any ideas?

Answer
I would check base idle first and ensure it's set to specifications (see service manual). I would then look at the idle switch (located in the throttle position sensor) and ensure that it indicates closed throttle when the surge occurs. Look for vacuum leaks and that the throttle body is clean around and on the throttle plate. You could also have a bad idle motor, and a continuity check of the circuits in the motor would be advisable if the first items don't clear it up.