i have a 1999 Chevy Express with a mind boggling problem.?

my van was running poorly (ran fine at idle and it ran fine if you babied the gas pedal but if you gave gas quickly, it would choke and sometimes stall). so i put a fuel pressure gauge on the rail and it was quite low. yesterday i put a new fuel pump in and she fired up a little rough but a lot more power than before. i drove it about 3 miles round trip and as i pulled into my driveway, she stalled. it won't start now but the fuel pressure is still there at the rail.
any help would be great!!