92 T MKiii. When it's at normal driving temp the idle sometimes likes to drop to around 600. Sometimes even stalls out. As far as I can tell the way I drive doesn't seem to affect this. No idiot lights, no codes. any ideas??

could very well be a vacum leak, check your air intake path and hoses.

yeah ide check everything for vacuum leaks.. I built a leak tester for 4.00$ that found 3 leaks I didnt know about..
600rpm is about the right idle speed for a turbo.. what does it normally idle at?
you should take out your ISC, clean it really good and test it.. adjust the tps too..

check all of your wires that bring the electric to the ignition coils