ok, I have been carrying this for a few months now. I had done testing with a fuel gage and the pressure was just fine. I did more test yesterday and I notice that the pressure actually builds up to about 49 psi, but as soon as it goes up it will start dropping like crazy, thats with the key on "on". Also sometimes when I had it on start and is cranking the pressure would be close to 0, and fluctuating up to 30 then it would be at 49and finnally starts.

If I leave teh key on "on" pressure comes up, but then down.
Never had any other symptom one it is running.
I think it is the Fuel pressure regulator check valve or the check valve at the bottom of fuel pump.
Any idea????

02 KJ V6 mfg MAY 2001, 75k miles on it.
if you have questions let em know.

DONE.
I replaced the pump, I was unable to change fuel filter because, i needed an extra set of eyes to help me hit the lil nut.
Seems that the ploblem is solved, I changed the pump and sending unit.
Now it is holding the fuel pressure for about 30 minutes or more.
I will do a write up, w/o pictures (sorry I left the camera that day)
Hope this helps.