Wife's 2007 Cobalt 2.2L with auto trans has been running sluggish on acceleration, coolant temp not registering on dash occasionally. Hard to start occasionally. Over the weekend it stalled it while leaving the store. Turned over but no start. Tried several times, ever tow guy tried, no start. I heard tow guy banging on something, now I know it may have been starter? Get it home, check most fuses, still nothing. Unplug battery overnight, next morning Now No Crank!! Where should I troubleshoot? Saw so many issues with this car online about my symptoms I don't know where to begin. Had battery checked an charged. Nothing. Lights work, I here fuel pump prime. Had a buddy connect the post on the starter and it spun. However we think the 'plunger' didn't engage. Could it just be starter? Why did it stall out? BTW I changed camshaft sensor and will change crankshaft sensor if and when I remove starter. An advice would be of help and greatly appreciated. Thanks.