2003 start but no run

i have a 2003 zx2 119,000 miles was driving the car the other day and had a little pop noise like a back fire under hood, car died pulled off tried the key engine will start butr run only at 500 rpm then dies roughly, towed home checked timing alignment looks good, check fuel pressure key on engine not running, peaks at 60 psi the drops to 45 psi disconnected fuel injectors sprayed atomized fuel down throat while cranking back burps out the intake.
anyone got any ideals, by the way no check engine light ever came on, i have noticed while driving car at low speed (in town will shut off or loose power) for brief period then resume normal, like somebody shut the fuel off.