Rough Idle, Low Power, No CEL - Resolved
2008 Cobalt SS automatic had intermittent rough idle, reduced power and when accelerating would sometimes lag and eventually kick in. Worse on incline. No codes, no CEL.
Resolution - changed plugs (very old) and cleaned throttle body. All fixed, runs great.
When cleaning the throttle body, lots of black deposits!
DON'T SPRAY INTO THE THROTTLE BODY!
Soak rag, use rag and finger to thoroughly clean every surface. Must be shiny and smooth.
Original AC Delco plugs, very gently verified gap.