hello...
First do a search on here, there has been a lot said about this. Second, i get the impression that this is a very sudden jerking, and thats VERY bad. Take it to the shop now! I know with mine that they didn't have to replace it, they just put in a new torque converter and fluid. They also had to reset the computer (duh) but most importantly they found some old notice about a problem that can occur with our tranny type, something about a program error or a slide/guide that doesn't work?? I really should have found out more about what they did but it was before I found the yahoo mx6 site so it didn't seem worth asking about.
All of those other suggestions are more like preventative measures. I would also suggest that you avoid using your hold button for any reason, and doen't race ALL the time especially up hills.
My 2 cents,
Cya,
Claeren.