christopher breed

'08 Tahoe ..Same... started 3 days ago. slow turning over when leaving work. Drove fine home. Started the next day and barely turned over ran very rough. Fuel fumes, no RPM's on the tach, service stabilitrack, VERY rough shifting into 1st gear. Parked for a few days and scheduled to take it in. Jumped it with my new NOCO jump battery (very cool). It ran perfect to the mechanics. Perfect. Shifting fine, RPM's on the tach. Ran like nothing had happened. Left it at the mechanics and called to get the scoop. Needs new battery and needs software update? $650. Sounded like alot to me. Passed on the repair. Ran rough all the way home. Can a bad battery cause all of this? the pcm? What can make it suck one day, run prefect the next day and then suck again?