I have a 2006 Cobalt LS, and like the title says it has a really rough idle where the lights flickering and I'm getting both a P0300 code and a P0650. I just got the car a few weeks ago, it as almost 100,000 miles on it now. Sometimes it runs almost smoothly with very little to no flickering lights, other times it's bad. It also stalled on me one time while sitting in a parking lot, but that hasn't happened since. I'm thinking it might be a bad ground, possibly behind the instrument cluster due to the P0650 code. Does this seem like a reasonable suspicion? And if I pulled the fuse to the cluster and started it up, could that possibly confirm anything?