If you have 37psi fuel pressure with the vacuum hose attached
and 44 not attached, I don't think you're problem is the fuel pressure regulator. That's exactly how it should work.

Have you checked your fuel filter?

You also might want to check your EGR and make sure it's not
plugged up. It will cause a loss of power if it gets plugged and doesn't function properly.

1995 Trooper LS auto 3.2 DOHC /w SOHC intake
1989 Trooper 2.6 auto
1989 I-Mark RS DOHC 1.6
1991 Stylus XS DOHC 1.8