Could be any number of things from a engine misfire to transmission problem. Any lights lit up on the dash? Maybe have a local mechanic diagnose the issue?
Agree. Always scan for trouble codes first. I've found cleaning the throttle body helps to a degree although it never eliminates the problem. And of course there are a number of problems that could cause that. It's a common complaint among Cobalt owners. I haven't followed my own advice and checked for codes though. For now I'm content to put up with it an be annoyed since it only happens in first gear.
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