my buick runs great cold but as soon as it heats up it loses power arter it get on 1996 Buick Regal

if i put the pedal to the floor it kicks in again idles great but when comes out of first gear it just gois flat with no power at all til i punch it and it kicks in and again like its starving for fuel ran diegnostic and code was p1441 i have changed the fuel filter fuel pressure regulater and purge sensor problem still exist please help

Asked by for the 1996 Buick Regal