Fuel Pump Failure or Oil Pressure Switch???

Hello and greetings to all,
I'm having what appears to be a fuel starvation problem with my Suburban. I was reading that when you first turn the key, the fuel pump comes on to prime the fuel system for starting, but must have signal through the OIL PRESSURE SWITCH to keep fuel pump (and engine) running after starting.
I just bought a 1990 Suburban off eBay and towed it home to Michigan from Ohio. The other day I was flushing the transmission in the driveway while it was idling in drive when it suddenly stalled out. I had no idea if it had run out of gas because the fuel gauge doesn't work(needle stays at 3:00 position, past full) Anyway, I put 12 gallons of fresh gas in the tank and since then it starts and then stalls right away. If I try to keep it running by feathering the gas pedal, the idle stumbles and goes flat when pressing down and then when I let up, seems to breifly raise in rpm before stalling out. I changed the fuel filter yesterday to no avail. It has new rotor, cap, wires, plugs, battery. The fuel pump runs when I first turn the key and the injectors are spraying while cranking, during start up, and continue spraying until it stalls. I have read so many posts about fuel pumps being blamed, but I'm not entirely convinced that is my problem. It seems something is shutting the engines fuel system down and the oil pressure switch sounds right. I'm curious if that is what it is and where it is located? Thanks so much in advance for any reply.
P.S. I've gotta get this thing road worthy soon...my wife keeps opening the front window and yelling out "Piece of junk!" and I can't take her ridiculing much longer!!!

I want to add that the oil gauge does give a reading of about 30psi during cranking and when it first starts. Does this rule out a bad oil pressure switch?
Because the fuel supply line and return line are hard lines and had no flexablity, I removed the TBI from the intake manifold to connect some rubber fuel line to the supply line and put the other end into a bottle. When I turned the key forward(without cranking) some gas pumped into the bottle, but not untill I turned the key forward a couple times. The coil wire is disconnected but I haven't tried cranking the engine over while observing. There is also no valve like on a fuel rail for checking pressure...I don't have a pressure gauge anyway. Hope this addition can help someone diagnose my problem. If anyone still thinks it's my fuel pump, don't be afraid to chime in and tell me so! I'm open to any help I can get!!!

Happy New Year!!!,
Today I went out to the burb and cranked it over and observed the fuel flow into the Coke bottle......it was pretty much a continuous flow through the 3/8 hose, but didn't really have a lot of pressure behind it. It was more like a stream that you would get from siphoning gas through the same size line. Does this seem right to anybody? Also ran the same test with a wire jumper between the positive terminal and the fuel pump test connector located on the firewall above the pass. cylinder head...same results. Should the fuel be SHOOTING OUT or just a flow because the system is open?
Also, the two sloted ports on the backside(rear) of the intake plenum's are pluged with carbon. When I removed the TBI last night I noticed this. Can I clean these out with the manifold on the engine? Any tips or feedback about this would also be helpful.

Well, I made the decision to drop the tank because I need to redo and re-route my trailer wiring to accomodate the Pullrite hitch I got off eBay.
Man, those strap bolts are a bear with 16 years of rust on them. I bought an aftermarket Carter Fuel Pump from the local Murray's and it only ran me about $40.00. I'll be using the existing hanger and sending unit and just replace the pick-up sock. The pump even came with a new wiring harness!
I ran out of daylight but hope to have it back together soon.

Hi, if the fuel pump didnt work, and your looking for the location of the oil pressure switch, it should be located on the rear of the engine near the distributor on the small blocks (350). It can be a little hard to get at. keep us posted. Good luck.

Yep, that's what it was...kind of.
The pump wasn't actually the problem , but rather the little piece of rubber hose that connects the pump to the steel outlet tube! The pump had already been changed by someone in the past and was still working fine. However something must have been introduced to the gas that was harmful to rubber. The rubber foot that the pump is cradled in was a gob of goo...I didn't even know what it was at first. The pick-up sock had crumbled in to pieces and was totally ineffective. But the source of my problems was that soft, gooey, piece of swollen rubber tubing with a crack in it's side. Half of what the pump sucked up was getting pumped right back into the tank through the crack in the hose!!!
Thanks

Good to hear you got it figured out. Did the previous repair use the right rubber hose? It has to be fuel line, which is different than ordinary rubber hose. Could have been the reason for the failure. Fuel pump repair is no fun to do, since one has to drop the tank. I have done a few and dread it everytime I need to do it. Fortunely the pumps last for a while. Anyway, good to hear you fixed it. Have a good one.