Ours shifts very softly. The mechanic who rebuilt it and has checked for this problem is an automatic transmission specialist who is regarded as one of the best in our area. I expect he'd have the right scanner etc. It's just that the malfunction cannot be reproduced on demand, and it's infrequent enough that I can live with it.Limp mode from the moment the car starts has a good chance of being an electrical/sensor problem.
Limp mode that happens after a lurch is likely because of a low pressure situation. Low pressure causes hard shifting. The revised TCM was more tolerant of low pressure and adapted accordingly resulting in less hard stuffing, bump stops and limp modes.