ok well its not really an idle issue, I have a M6 Camaro but what happens is i will be cruising and then push the clutch in to come to a stop and the idle will drop to like 600 rpms. but the issue is it only does this occasionally, it will do it mainly when im in first or second say going from stop sign to stop sign the it will drop and sometimes it will be fine and go down like it should. I dont think its a vaccum leak cause it would happen all the time, i have a leak in my exhaust where the header meets the X pipe could that be the issue?? or could it be the shitty tune i have??

 

could be vaccum and or tune. I have the same problem in my A4 but its the factory stall.