sounds like you have the wrong fuelpump.if pump has not been replaced , there is a major problem causing the pump to generate to much pressure wrong fuel pump, or a clog or restriction at some point in the fuel lines.
In a 1991 3.3l the oil pressure switch is located beside the oil filter
could be a vacuum leak
A 1996 Plymouth Voyager does not have a cabin filter.
The fuel filter is located under the car at the back near the gas tank on the passenger side. Just look for a small alummium canister with two hoses going to it. These are quick connect fittings.
You have to fabricate fittings to splice into the fuel line at the fuel filter so as to install a fuel pressure gauge. Not uncommon to do with older vehicles.
could be the magnetic pick-up in your distributor, I replaced mine and it solved the problem.
Probably because it is clean, leave it on the filter setting for a while and you will find that the pressure will increase as the filter gets dirtier, when it get high (usually in the red ) you will have to backwash.
The oil sensor is on the forward side of the block ,just above the oil filter
Bad news, the filter is part of the fuel pressure regulator on the of the tank at the fuel pump module assy. It ain't real easy or cheap.
It doesn't have a test port. You have to fabricate fittings to tap into the fuel line at the fuel filter to connect a fuel pressure gauge. They probably sell a kit to do that but I made my own.
Fuel pressure regulator.
You probably have a clogged fuel line or fuel filter. I'm not sure what you're referring to when you say fuel filter regulator but I'm guessing you mean pressure regulator for the TBI. Tear down TBI and give it a good cleaning carefull not to scratch or gouge anything.