2005 Chevrolet Cobalt

Engine Performance problem
2005 Chevy Cobalt 4 cyl Two Wheel Drive Automatic 105000 miles

My Cobalt stalls when make sudden stop or stop light. It seems to do this only once car is warm. The idle ( RPM's ) drop real low then sometimes bounces back up then shakes at low rpm then stalls. The check engine light is on all the time. Took it to a shop to have it read. The only thing they found was a message the mass air flow sensor needed replaced. I did that. I disconnected battery to reset engine light. It worked for a few hours the light came back on. $ 90.00 waisted, and problem not solved.
Where else shoud I look?
June 2, 2010.

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