Merv,

Not to ask the obvious but the following questions....

1.  How many miles on van?
2.  What service has ever been done to the tranny?
3.  Have you considered getting the screen changed and the fluid
changed?
      (auto trannies must be the most ignored components in a car until
they die, then people complain about their reliability.  It's always
interesting to see a new car manual that says its ok to change the fluid
only once in 100,000 miles, but that in 'severe service' it should be
done every 20-30k.  Hmmmm, what constitutes severe service?  With the
hills around my place, that's probably one of them!)

Regards,