Engine/Transmission (1998.5 - 2002) Overflow check valve replacement, is it bad?

[MRose]

I have had a hard start issue that I've been trying to track down. My fuel pressure dropped to 0 as soon as I would shut off. Took old valve out and was able to blow through easily, cleaned and blew with compressed air and seemed to work, fuel pressure dropped slowly then. replaced for good measure. New valve the pressure dropped instantly after second start, flushed lines for more good measure, blew new valve out, seemed better but still have same issue after second start/shutdown. Hard start not solved but the seals are bad now after all the r&r. Thanks for the help!