First thing I would check is the computer ground. It should be bolted to the passenger side of the intake manifold. Where the intake and the plenum are bolted together.
The next thing would be the AIR FLOW METER, this vehicle does not have a MAF. The air flow meter is on thwe drivers side and is a big metal looking box that the air intake connects to. As the air enters the AIr FLOW METER IT MOVES A DOOR INSIDE IT. There is a SPRING on this door that is used to keep it closed. IF THE SPRING breaks it will cause a condition like your describing. Take the AFM off and make sure the door springs back closed if you push it with your finger.The AFM also controls the contacts that make the fuel pump run. You should also get a manual and check the CIRCUIT OPEN RELAY, it controls the fuel pump from inputs from the AIR FLOW METER.
Make sure you have the fuel lines connected prperly to the the fuel filter, it definatly wont run properly if you have them backwards.
There is also anopthe ground wire bolted to the cylinder head on the drivers side just below the piower steering pump, make sure its also connected.
Start here and let us know what you find out.
What did you do to "BYPASS THE ECU"? That doesnt make sense, without the ecu the engine wont run.
The engine will not shut down if the oil pressure is low, it only shuts down when the engine seizes.
That was only applicable to the old (circa 1980 vehicles), also make sure the idle set screw on the throttlebody isnt turned all the way in, and make sure all the vacuum lines are installed properly.
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