my tranny while driving at any speed when take foot off gas, slips and bangs

What is your question?

I mean sometimes really if I don't catch it violently slams back into gear it has broken all trans mounts (replaced)and three engine mounts which I now have to replace them all again. it dosnt happen all the time and it cruises perfectly on the highway someone said moduals no codes have ever come uo and im at a school with the top three scan tools available thanks for your time in advance