Still waiting for GM to call me back for over two weeks now due to a problem related to bulletin number PI3146B. On cold starts the car revs up and down on high idle. They said it was bad fuel and drained the tank flushed the lines and added an additive. It worked until I filled up again (SHELL) and the problem started all over again. I brought it to the dealer again Wednesday 5/28/08 and they had no resolution for the problem that GM engineers were working the issue. I switched fuels and the problem has gone away for now but for how long. They said it was either water or high alcohol in the fuel made in the SE region.