Can’t properly diagnose and fix

What is your question?

I replaced my transmission and now my car randomly won’t start, gauges go up and down randomly and I experience slow acceleration. Took to a mechanic he said it was the bcm, after he got it diagnosed at the dealer ship. Still had the same issue. Took it to triple AAA they said my battery terminal was off and needed to clean. Still having the same issue. Took back to triple AAA they said it was the pcm

What makes this problem better or worse?

Every time it’s goes through a diagnostic all the codes come back fine

How long has your 2012 Chevrolet Traverse had this problem?

More than a week