[kmohr3]

I would have the car scanned and see if there are any trans codes that have been stored first before disassembly. I believe it can be a substantial amount of work to get the valve body off. It's on the driver's side of the transmission and sits vertically under the pan. Also a logical guess would be the Pressure Control Solenoid Valve assembly - this can be affected by heat and affect shifting.

I was a dealer VW/Audi tech for many years, and after reading the side pan removal procedure in my GM factory manual I don't think I'd want to do this job at home. Maybe there are shortcuts, though?? How about it Panzer? Does AllData have a transmission side cover removal procedure? Has anyone pulled the side cover and/or valve body off at home? Good luck and keep us posted on what finally fixes this car.