i have a 2002 gmc sierra with a 4.3L 5spd. on some cold mornings ill start it from a cold soak over night and the idle will hunt quite a bit. go from 900 to 300 and back and forth over and over for about 15 seconds or so. thing sounds like its cammed up. i cannot find any vacuum leaks and sprayed the intake with carb cleaner. i had this happen in my 93 w/305 and it was the ignition module in the dizzy. but this doenst have that correct? anyone got any ideas?