Ok here's the deal....my truck is running fine but the tach is fluctuating from (idle around -100 rpm) and (constant drive speed 1000 rpm) im thinking its my cluster....? but thats a shot in the dark.....could be some computer problem? the other night i was running my buddy in his duramax and when mine shifted down from 3rd to 1st the rpms jumped from around 1500 to 6grand.....i backed out...just thinking something was going wrong....this crap is pissing me off!!!!! if anyone knows whats up or has had this problem let me know
(03 tahoe 2wd) just if you needed to know

 

GM is having problems with the clusters - just get a new one.