Report "My 2002 gmc envoy runs rough sometimes. This morning on the way home from work it was missing a little and the check engine light was blinking. I just got in it to take it to a service shop and now it runs perfect. I don't know if it has anything to do with it but a couple of days ago my altenator quit. Replaced it and now its charging the way it supposed to but the rough idle had started before the altenator. What is wrong?"