Altough gearbox is Mercedes you can't go and buy valvebody from MB. What I've gathered that they are slightly different.

 

After a month of trouble free motoring the hard shift is back, happened twice. Once after parking and restarting the car and once after driving for a while and pulling away from a drive through.

I've noticed that when it's going to happen it feels like the torque converter is locked and not freely spinning when decelerating. It feels like I have engine braking like you'd get on a manual transmission. The car won't stall out but you can feel a significant drag compared to normal driving where it feels like the torque converter allows the car to free wheel. If I then accelerate I'll get the hard shift first to second. Only happens once and then it'll be fine for the rest of the trip.

I'm thinking I'll drain and refill the fluid and replace the filter and the connector. Anyone got any other suggestions?

 

It is known issue with 5g tronic where turbine lockup is not releasing propely and stays on at least partially. This causes numerous issues where tcc is still on and gearbox changes a gear. Cold start stall or in my case hot start stall. I too had old school shift kit -type gear changes and other weird things.
Remedy was to complete overhaul the turbine and install a return spring modification.

 

Torque converter clutch solenoid could be going bad or pcm/tcm commands are glitchy. If you can get a reader to see the tcc solenoid driver amps it really helps

 

Did the drain, refill, filter replacement and the connector. There was some fluid in the connector. Been a few weeks and not had it reoccur. If posting that it's fixed doesn't make it immediately reappear then I'm going to declare victory.

 

Excellent