My car idles really low, but it wont just dip down and come back up (like when you change gears) it does it for long periods of time after it warms up. It will just drop to 350 or 400 rpm. It does it more frequently with the ac on. ANyone have any ideas? Could this be a vacuum leak? i though those raise idle speed?

 

well my formula will be about 900 while its warming up, and about 400-450 while its sitting at a light

 

it might be a vacum leak...might did that when the throttle body was leaking, but i was able to hear it

 

Maybe your tach is off a little. I think mine was off by 200-250.

 

Mine does just about the same, just got used to it. Plus sounds a little lopier.

 

I thought vacuum leaks made the idle higher?