S80 2005 AW55-50 disengages while driving

[fic]

Hello!
Have read hours and hours about this gearbox problems, but not having any solutions of the same issues.

Having this problem with two gearbox changes and we´re out of thoughts of my mechanic friend.

Bought an S80 2005 with broken gearbox which got stone under the front end and broke the gearbox. Rebuilt new gearbox and changed clutch disks and of-course new oil. Everything worked fine but Adaptions with Vida failed. About 150 miles later gearbox disengages in town-speed. Revs go up but moving hard and after few moments not at all. When restarting the car, it worked again for a few moments. Thought the filter is full of mush.

Changed the gearbox (which was welded and already ready with new filter) and put the same valve body from this car. With previous valve-body it didn´t work properly.
Everything worked fine, except some harsh gear changes from 3rd to 2nd like it was before with previous tranny. Okay, that´s not the problem at the moment. After 150 miles when got from 50 miles road to city, then car revved 2500-3000 some times and when stopped and accelerating it revved and moved slightly. Turned off the car but the problem was same. Managed to get home and when checked the ATF level (did it correct way), it was 3/4 inch above HOT upper mark. I let it cool down and checked in the morning it was 1/2 inch below lower COLD mark. Drove it for 15 minutes, everything worked fine, accelerated nicely but then suddenly disengages and no power, just revved. Oil level was same as last evening 3/4 above HOT.

When cooled down for 3-4 hours managed to drive for 15 minutes and then again all the story. When turning off and on everything works fine for a few minutes. All gears are gone when putting to Reverse.



For us it looks like electrical problem, because when cold, works fine but after reaching working temperature, problems start to occur. Doesn´t seems to have solenoid problem either. Have read it could be TCM (Which missing communication code it has). What to do with TCM, buy new/used one and reload the software?
Why the ATF level varies from below cold to above hot?

Any thoughts? What to check?
Thanks and waiting for thoughts.

Kindest,
fic