I have too have had the idle drop problem about 3 times, where would the control you talking about be located? and how would you go about cleaning it? also, are TSB covered by GM? even if your vehicle is out of warrenty? I also have the high reving, jet engine sound every now and then but it seems to just happen to me when I first start it up and quits after a few seconds. any recommendations on how to replace the clutch fan? and a good place to get parts?