Yes definately sounds like what I had. What you will find is that as the car/tranny heats up, the coolant hose feeding the trans coolant box from the radiator is not working (blocked hose/faulty valve) so the trans fluid is heating up. A simple test is to read the temp of the tranny box cold and then after 30 mins - you will see the temp is above 100C (it should be in the 90's). This causes he tranny fluid to thin and then not function properly, hence the jerking motion.

The fix is relatively simple - replace/ remove the valve that feeds the coolant into the transmission system or unblock the hose - relatively cheap to fix. Just make sure the fluid has not leaked, otherwise you will have to replace the gasket.

Fyi I had my whole autobox reconditoned from a ZF specialist and works like a charm (but you dont need this to solve your issue).

Let me know how you get on.