1994 Caravan 3.3 Won't stay running

Just picked up a '94 Caravan 3.3L, 150,000 miles. Previous owner said it died one day and they couldn't get it running again. They replaced plugs, wires and fuel filter, to no avail. Finally they gave up and now it's my problem. Charged up the battery yesterday and turned it over. It'd start and immediately die. Checked fuel pressure, it'd go up to 20, then trickle back down within 30 seconds. Pulled vacuum hose off of regulator, full of gas. Replaced regulator today and now it'll start and if you keep pumping in a specific rhythm, it'll keep running, but very poorly. Sounds and smells flooded. The fuel pressure will go right up to 50 before you try to start it, but I couldn't check it while it was running since I don't have a giraffe neck or an elaborate mirror setup, but if that's required I'll get some help. I'm leaning towards either a stuck open injector or a bad check valve in the pump since the pressure begins to drop and heads back to zero with in a minute or so as soon as the pump stops running. Anyone have any other ideas or know how to narrow down my leak down problem, I'm all eyes. Thanks for your time.

Check this link out: http://www.autozone.com/az/cds/en_us/0900823d/80/10/c6/09/0900823d8010c609/repairInfoPages.htm

Have some one help you try to start and watch your fuel pressure gauge. If it drops while cranking I would say it is bad fuel pump.

Hope this helps

Update time:
This evening I removed the upper intake plenum so I could see the injectors to check and see if any of them are leaking and they aren't. I pinched off the return line and ran the pump. The pressure went up to 50 and then relatively quickly dropped back down to zero again. Next, I ran the pump up to 50 and then hustled over and pinched off the feed line and the leakdown stopped, just sat there at around 35 or so (which is what it was at when I got the clamp on the line). As soon as I took of the clamp, pressure dropped right back down. Haven't had a chance to get an assistant long enough to check cranking pressure, but I'm pretty sure I'm gonna need a pump. If anyone has any experience with these pumps and knows if there is a check valve to keep the line full or I'm missing a leak or some other info, I'd appreciate it. thanks

Decided to jack up the van and spray down the tank straps for the pending tank removal tomorrow. Decided to take a good look at the feed line up to the engine bay and noticed that someone previously had replaced the fuel filter and must've used non-high pressure hose for transitions to and from the filter, because they were both split. I'm pretty sure I found my problem. On to the next problem.