Why won't my 1992 Ford Econoline van start

Stalling out
https://www.google.com/search?q=1987+Ford+E250+stalls+out

Bad gas mileage
https://www.google.com/search?q=1987+ford+e250+bad+gas+mileage

Expected gas mileage

Gas Mileage of 1987 Ford E250 Econoline

Fuel Economy (.gov) https://www.fueleconomy.gov > feg > bymodel > 198...
1987 Ford E250 Econoline ; 6 cyl, 4.9 L, Automatic 3-spd · 14 · 13 · 15 · 7.1 gals/ 100 miles ; 8 cyl, 5.0 L, Automatic 4-spd · 13 · 11 · 16 · 7.7 gals/ 100 miles ; 8 cyl, ...

It may not have anything to do with the tank switch. It sounds like the check valve in the pump has failed. The valve prevents fuel pressure from draining back into the tank.

I think that if you have a carby system that I would be checking the auto choke operation. IF efi I would be running fault codes looking for sensor problems in the air intake area. Check the duel switch and ensure that there is not possibility of an air leak allowing fuel to drain back in the system as replacing the unit appears to be the start of your problem

how can you say that you have power going to the coil and lot leaving it and still say its good?
kinda answered your own question there i think
just my opinion...
hope this helps

Most likely your (TPS) is out "Throutial Posision Scensor".

Your van does not have OBD, but it does have a EEC-IV and MCU connector sit under the hood near the battery, will have a cover over the connector small black cover will read on it (diag. connector).Hope this was very helpful.

you may have bad gas which can cause all these problems ...stale gas has a very sweet putrid odor...check that first

behind rear 1/4 panel trim

did it run when it was parked?
and fuel pumps will go bad sitting for that long!!!!

Verify the vacuum hose to the sensor has vaccuum to it,while engine running. Do a scan on the computer and post the codes....