fabdad

My 98 Avant A4's transmission is struggling to downshift when tranny gets 'hot' (1+ hr of driving time).

A more bearable symptom is occasional 'clunky' up-shifting too; but when transmission gets hot (extended driving), it often fails to downshift and remains in high-gear and thus: stall when coming to a stop and become nearly impossible to regain speed again from a stop trying to start in high-gear.

Apart from full transmission repair/replacement, is there any other recommendation for me? Wondered if the 'vehicle speed sensor' may be suspect?

Car details:
Location: I'm in/near Denver; car is now in Durango with my daughter.
Transmission filter & fluid were serviced/replaced within last 2k miles.
Mileage: 119k
Can have codes pulled but not able to do so at this moment.

Prospeeder

Sounds like the valve body has sticking valve or solenoid. You could as a low cost remove the valve body and remove each spool valve and see if it binds in a hole at all. Or buy a reman valve bod. Study the way the transmission works and if theres a solenoid that controls that down shift it could be faulty and try replacing it. Or when the transmission is very hot and acting up quickly pull the pan and check all the solenoids resistances and see if one is radically off. There may be schematics out there of the connector on the trans and could check solenoid resistance there.