Shortly, after driving the car for a while (30-40 mins in city), I would come to a stop and when I step on the gas again the car would not move first, with increasing rpm it would jump eventually causing a TRANS FAIL SAFE mode.

I have changed, transmission cooler, battery (alternator checked ok), transmission speed sensor (because of P0720), transmission valve body, neutral safety switch and nothing solved issue. I also suspected interference from aftermarket sound modules and unplugged everything with no results.

Transmission guy told me there is a problem with the control module, I have just purchased a used module (same serial number etc.) and about to replace it tomorrow to test it (hopefully no programming needed). If that does not solve the issue the only thing left is an internal problem with the transmission, but lets see..

Ozzie