Fuel pump pressure and hard starting

Hi, I have been going nuts with this van and was wondering if anyone has any ideas on the problem. Last summer it would not start, random problem after it had been running, let it sit for a while 30 minutes or so, then start right up. Finally in the fall it was blowing the fuse for the fuel pump, so I changed the fuel pump in tank, used motorcraft brand new unit. Ran fine after that. A few months ago it started to do a hard starting routine, first or second cranking, nothing then it would fire right up and run fine. I used a fuel line pressure tester last week on it, results as follows:
Hooked it up to rail, 0 pressure
key on, pump relay kicks in 2 seconds pressure goes to around 10
off on, pressure climbs to 15-20
off on, pressure to around 30 it will start no problem there
Running with pressure regulator (I just changed that as well) connected to vacum around 38 and holds steady
Running with regulator unplugged 45, runs fine.
Shut off engine and the pressure drops to 0 in about a minute with the regulator was hooked up, with regulator unhooked it was running at 45 it will hold the pressure at about 45, very strange.
What would cause the pressure to drop to 0 all the time, think I have a defective check valve in the new pump? can't see or smell any gas leaks. Van runs great, it has pleanty of zip, just that hard starting thing.

I also replaced the pump and PCM relays in the fuse panel.

Any ideas would be greatly appreciated.

Thanks