I would start by looking over the vacuum system and I would start by re-working ALL the vacuum connectors. Good vacuum to the transmission makes a world of difference on these cars and it is cheap and easy to do.

My transmission was flaring badly and was related to a vacuum leak at the EGR valve...turned out to be 39cent fix....search for EGR valve also. There is also a short piece of vacuum hose connector down on the transmission going to the modulator valve and one up top right behind the fuel pump. I found great piece of mind by just replacing ALL the vacuum connections I could get to...total cost was under 20 bucks and BINGO a lot of stuff started working better, like the transmission, door locks, vents, and fuel door lock.

Well worth a shot.

__________________
Mark
1983 300TD Wagon
Even a broken watch is right twice a day