2007 2.8 cts with 82,000 miles. Rough idle. Bad fuel? Fuel filter? Throttle body? Air filter. Only gets jerky when stopped at light in drive. It auto. When driving it is fine. Fuel injectors? Maf sensor?

 

My process of diagnosis that works:
1) Check codes at any auto parts store. That will show if it's a bad sensor or otherwise.
2) Check filters. Usually the cheapest repair.
3) Fuel injectors can be cleaned by most auto repair shops for under $150.

TS