Check engine light on says something about the cam shaft out of balance. What are they talking about
It sounds like there’s a discrepancy between the camshaft position sensor and the crankshaft position sensor. Pontiac G6 P0016: Crank/Cam Position Correlation – Bank 1 Sensor "A" | Drivetrain Resource A faulty sensor can cause it but you need a real mechanic with hands on the vehicle.
It could also be a problem with the variable valve timing actuator. Assuming your car has that gadget, which it probably does. Especially if the routine maintenance oil and filter changes haven’t followed the manufacturer’s recommendations for the intervals.