Ok so now what??? long

As reported in xjvenoms thread about running hot since engine upgrades I have the same problem except I run about 215 or so all the time well I finally got a pressure guage and indeed Im running low on fuel pressure....After letting it sit all day and all night and testing it this moring I find 0 pressure in the rail(no suprise here) after turning the key and starting the pump it went up to 40 psi the slowly dropped to 38...The I took the key out and tried it again this time it started at 38 and I started it up it kind of stumbled for like 3 secs like it has been then idled just fine at this the pressure was down to 36psi and holding WTF shouldnt I be at 39 steady???? Is it my pump, my fuel regulator??? Im not sure how to test either one....

Some help here would by great, After doing some research I have come to the conclusion that just cant get enough fuel for my new set up and Im debating whether or not to get a map adj or a adj fuel pressure regulator...Either way I dont need to change injectors as I had them cleaned and rebuilt and they pressure tested them to 60 so I know they can handle an increase in pressure...Given current gas prices Id rather be fighting a lean condition than a rich condition :doh: ....Im leaning towards the adj pressure regulator due to the fact that even if I crank up the map voltage Im still stuck with 39psi max (more like 36 with what its doing) and that doesnt help me at all now I could do both but I dont think just the map adj would help, right?????