Thanks to all who answered!

And here another follow-up from Sue:

"With the help of everyone - we started narrowing down the problem. Of all
things - it seems to be a small part in the fuel pump that is the culprit
(new pump, bad from the start). But we have alot of great resources do to
all the ideas everyone had - I have a folder full of useful links for the
allison thanks to everyone. Sue"

- Holger