Are you sure that the trans shop did not:
-break a vacume line?
-break an wiring conector?
-sell you a sick trans?
[these is my guesses if the van worked fine until the trans broke,
but then I don't do automatics]

I have experianced limp home mode due to a design flaw in a vw van, but the problem existed since it was new.
[and vw customer relations is worse than fords by a mile.
if it costs to much to honor the warentee, they don't,
knowing most people don't sue]
In this case I needed the vw part "engine missfiring wiring harness", which was a $500 fix for a defect that VW would not admit to having made to all US 91 vanagons.

Back to Ford:
I think that you need a ASE master with a computer to find out what is going on.
If it was the trans shop, you need something in writing.
You can probibly find this mechanic at your local ford dealers competition, the next closest ford dealer.
David