A question for those with Auto trans experiences:

My '89 with 120,000 miles began a sudden and strange behavior 4 days ago.
When cold and first engaging Drive, it may shudder like a clutch might
(torque converter?)
When warm (oil temp @ 160f)and after driving several miles it may shift
late into third or appear to shift into third and stay in second then shift
into third.

What I know:
It's had the same fluid for the last 20,000 miles.
I checked fluid at idle, engine warm and it sits just above the full line
(maybe drain some off?)

I have a trans screen and rubber gasket to change out the fluid, intended
to do it over the holidays but have a few other questions on that one:  How
tough is it?  Looks like the fill tube needs removed, couldn't get the fill
tube loose from the pan via the big nut though...guess I need a pipe wrench
but that may bend the fill tube, OR leave the fill tube connected and just
lower pan to drain?  I've read the Bentley but it seems unclear on this
part of the procedure.

Any and all words of experience are appreciated.

Jeff Birk
'89 Wolfsburg GL
'82 MB 240D
'59 Commando Runabout - with tailfins