My car has 100000 miles.
My car has an automatic transmission.
Chevrolet released a Technical Service Bulletin about this issue in 2013. TSB Number:PI-1131. It suggests code P2714 may be caused by a stuck or non-functioning pressure control solenoid. If you've eliminated that as the cause and replaced the TCM, then yes, it does have to be programmed by the dealership before the adaptive learning function can be done.
If you'd like a second opinion on this, consider getting your car inspected by YourMechanic. They will be able to diagnose your shifting issue and suggest an accurate fix from there. Best of luck.
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