@SKanev that's odd. How many miles/kilometers do you have on the clock? Based on that description it sounds like a sticking solenoid, worn or clogged clutch control valve or worn torque converter. Has the car been used for towing?
How was the ATF changed? A professionell flush with special equipment, or more like drain and refill? And how did the fluid look and smell? Dark colour and a smell like cat urine would have been an indicator for worn clutches and also potentially clogged valves, as the TF80 doesn't have a filter.
The adaption wouldn't be that much of a problem if not done right, as the TCM is constantly adapting/self correcting anyway.
You could do a line pressure/stall speed test to check if the torque converter or the transmission is worn out. It's described in VIDA under Information/Cleaning, Inspection and Adjustment/4 Power Transmission/43 Transmission/437 automatic transmission/....
