Why does my Rpm needle move up and down when starting sometimes? on 2006 GMC Envoy

Almost everytime I start my car the Rpm needle moves up and down quickly and it sounds like I am giving it gas when I am not. What would cause this.

by in Mobile, AL on November 13, 2012
1 answer 2 comments
ANSWER by on November 13, 2012
poss throttle body issues do youhave a ck eng light on? if so scan codes and post so we can adv
COMMENT by on November 14, 2012
No the check engine light isn't on.
COMMENT by on November 14, 2012
THAT DOESN'T MEAN ANYTHING HAVE THE LIVE DATA READ