Where are you monitoring your fuel pressure? Does that Holley go right where the stock pump goes, or did you relocate the pump? Make sure all your fitting are on good and that you have no air leaks in the system. Take a good look at everything and try to see if you have any fuel seeping out anywhere. I'm assuming you tried changing out the fuel filter? It sounds like a bad pump, but it's worth checking everything else first.
Maybe a little late now, but whenever the VP44 looses fuel (changing fuel lines, adding fuel pressure guages, changing filters, etc) I always crack the suction side of the VP44 just a hair and then bump the starter (don't try to start) until fuel starts coming out. Remember, if you use this method, the pump will run for another 2-3 seconds after you turn your key to the off position after bumping the starter. This may not sound like a lot, but believe me, if you crack the line too much you can get a LOT of fuel coming out of there (especially if you have an aftermarket set-up like a FASS system or a Holley pump). Once you get the air out up to that point, tighten up the fitting (do this as soon as possible because air will just get back into the system if you leave this fitting cracked) and bump the starter again to purge any air left in the system. After that fire it up and you should be good to go! I use this method and I have gotten to the point where the engine doesn't even miss a beat.
Good luck!