After more checking I discovered it was going into "limp mode". When the
trans sees a problem it goes into limp mode and won't shift. However if
you stop and cylcle the key it works again untill you come to a stop and
try to go etc.

Could be many things I'm told and for miles on it the 2 tranny guys I
talked to said its long due for an overhaul.

The van is actually in very good condition. An older fellow drives it and
takes good care of it. He must not have pushed it much to get that kind of
milage out of the trans. But still its a 14 year old caravan with 200,000
miles on it!