You are pretty mistaken if you are assuming this engine relies on its throttle body to control rpm or even has an IACV. The throttle is wide open 10 to 20 seconds after startup and the rpm is controlled by the valvetronic lift only. The throttle body is for backup when the valvetronic shuts down due to error.
anyway, for the transmission, replacing solenoids is extremely easy, anyone with half a brain can do that, the real deal is testing the valve body itself for leak tightness (I use a vacuum pump and a lexan plate to test for leaks) - Then the drum bushings themselves are tested with wet air checks from the valvebody ports that bolt to the transmission, This is why I asked did you replace the bridge seal and socket seals that are between the valvebody and the transmission case.
Find someone who owns proper tooling and understands how hydraulics work, then find an ATSG or ZF service manual for this gearbox and tear it down to repair properly, The replacement parts you need are plenty, the whole friction kit, the torque converter, the seal kits, the bushing kits, and valvebody overhaul kit too. The solenoids need a jig to mount and air test at varying pressure and temperature to see if one is stalling.
Its a good idea to demagnetize them and purge them while servicing, but in Pakistan I would just get a new/refurb set.
I overhaul these transmissions regularly, they are not too difficult as the valvebody and EGS controls the shift intricacies but you need a good understanding on how it operates before tearing into it.
The bounce you are seeing is too wild to be a torque converter clutch. If you are hearing a tinking or rattle noise too then quite soon you will see a bunch of oil leak soon from the torque converter seal.