Volks,
  I have been working on a rather nice '91 GL, soon to be for sale.  The
last issue is the transmission.  If the van has not been driven for a
couple of days, the transmission is reluctant to get going at first.  When
I shift into drive or reverse I can feel it engage, but the vehicle moves
very little until I run it at 2500 rpm or so for about 30 seconds.
  Once it starts to pull, it works fine for the rest of the day, shifting
smoothly at appropriate speeds, etc.
I have tried a dose of Seafoam followed by a fluid and screen change.  This
approach has worked well for me on other types of vehicles with the same
problem, but not this time.

Can anyone offer a considered opinion about the cause of this problem?
Will I have to go into the trans itself, or is there some hope of a remedy
by changing the torque convertor or governor or cleaning the valve body?

Larry A.
W. Michigan