help please

[joshtazz]

i have a 1997 3.1 liter monte and it idles fine until warmed up it will bogg up and down until it dies but when it moves its fine
i got to looking at it and i cleaned the egr valve no luck then i went to the fuel pressure regulator and when i take the top cap off and plug the end with my fingure it makes my car sound the same and run the same even at high revs. so i was wondering if that was and dont want to jus go and buy it cause its an expensive part.
thnx