when i first got done my cam and the tuning it ran perfect. every time i would come to a dead stop the idle would slowly drop to 850 where it is supposed to be after the tune. Now all of a sudden after about a week of the car running good it idles weird?? When i come to a dead stop the idle will drop down to a little under 500 rpm and then pick back up to where it is supposed to be anyone have any ideas why its doing this?? ANyone have these same problems?