Chevrolet Repair: fuel failure efi, buick roadmaster wagon, oil pressure switch

Question
93 buick roadmaster wagon chevy 5.7l h/o engine.
car will start run 20 to 30 seconds most times and shut off.
other times will run till warmed up then shut down.
I myself have replaced the fuel pump, filter, and the computer. the repair shop has rebuilt the throttle body and performed fuel pressure tests. they only charged my 175$ because It shut off when they were bringing it back to me and they had to pull it last 2 mile home with a chain. I have tested the relays and injectors etc. I have also bypassed the oil pressure switch because it shuts off the pump at low oil pressure. It really runs great when running then just shuts off. I have never seen anything like it. if you bottle feed it she will run as long as you can stand there putting fuel down it. there are no codes either.the test plug shows 12v at cranck and then it quickly drops off to 3v then zero  something is telling it to shut off and not telling the rest of the system to. I am a very adept mechanic even worked at ford and chevy and have never had something so bizzare. perhaps I need to remove the jumper from oil pressure switch ??? it is from orange to grey wire.
I wish I had alldata instead of a haynes manual.
pleas give input If you have any ideas at all?

Answer
instead of buying 26' foot of wire and posting negtive commetns on a free help site.  go INVEST $$$ in books and a AUTO MECHANIC.
BRING INTO SHOP and GET FIXED.

if ya did all that and are looking for help on a FREE VOLUNTEER BOARD and post negtive stuff  like that.. GO ELSEWHERE.

These nice pple DO NOT HAVE TO HELP YOU>...........