Tested the fuel pressure and it's 44psi at idle and 52psi with the fuel regulator vacuum hose disconnected. FSM says it should be 38 at idle, and 47-53psi with the hose disconnected. That's 6psi higher than it's supposed to be at idle--higher pressure, more fuel past the injectors, higher idle. Sounds logical to me anyway.

The system holds pressure well; didn't drop a bit three minutes after shutting off the engine.

Suspects are the fuel pressure regulator and the fuel return line. However, since there is a difference in pressures with the vacuum hose connected and disconnected, it seems to me like the return line can't be blocked. But maybe it's restricted somehow. As far as I can tell, there isn't anything in the return line other than hoses and hard lines back to the tank. Is there a test for restriction, or should I just go ahead and replace the fuel pressure regulator?

1990 Monty LS 3.0 A/T LWB. KYB front shocks, OME rears and coils. 33x10.5 BFG Muds. 5.29, 2.85, RD110, RD46. 2 bouncys. Aisins. Monte Disco swaybar disconnects. GenII t-arms, idler arm, UCA's, V45W front brakes. 2in BL.