Dead wagon, hoping to resurrect it

[Doug Yoder]

My fiancee has a '87 5ks avant that we really like, but has had some
problems with high-end power lately (acceleration at >2k rpm is virtually
non-existant, and rough running at slower rpms).

That, however, is not (directly, I think) why I'm asking for help.  Last
night, we went to go to a friend's house and the car backfired twice, then
stalled and wouldn't start again (we had just pulled out of our parking
spot, and had to roll back into it).  So we took my '91 100 instead.

Today I tried to see if I could figure anything out.  When you try to
start the car, it will catch but then stall immediately.  There are no
fault codes (only 4444, of course).  There don't appear to be any vacuum
leaks, but I don't really know what I'm doing with the vacuum guage - I've
never used one before (I am an engineer though, and can pick up on things
very quickly if I have good instructions).  Occasionally when I try to
start it, the oil pressure warning light comes on, but doesn't stay on
(there are no oil puddles under the car though).  The oil level was low,
so I added a quart, but it didn't make any difference.  There is a hose
that runs from the air intake to the bottom of the exhaust manifold, the
plate that it mounts to under the manifold has completely disintegrated (I
don't know if this is related to anything, though).

Anyone have any ideas?  Anyone in Dayton, OH got some spare time this
summer and looking for a project? :)

Thanks in advance,
-Doug