If it's the W motor with that amount of pressure, check the harness connections (the ground wire as well). The plug-in (wiring harness) you need to look at is under the van just before the fuel tank. This information is based on what you have replaced already.
Check the "Gray" wire for 12 volts which it must have to run the pump properly. Also check the ground connection the runs off that harness to the frame rail of the vehicle, make sure it isn't corroded and has a good ground contact at that bolt that holds the wire onto the frame rail.
This area needs to be looked at (wiring harness) "before" the fuel pump replacement to make sure the problem isn't in this area as well. If your getting 15 PSI with the ignition "on" and engine "off" after replacing the fuel filter and checking the wiring harness, then replace the fuel pump at this point.
I hope this helps. Please keep us updated, Thanks.