Thanks for the tips jb1390. The pressure jumps to almost 60psi when I disconnect the vacuum line to the regulator. Engine runs smooth although the idle is a little fast (maybe compensating for the extra fuel?)
I also tried spraying carb cleaner into the intake when the engine was about to die - it pepped back up and ran smoothly until it was ready to die again, so it does indeed sound like a fuel problem.
So now the question is, does it sound more like the regulator or fuel pump? I disconnected the out of tank pump to see if the in-tank was firing and I could hear it when I turned the ignition on and I could definitely tell that the out of tank pump is firing as well when I reconnected it.
I wasn't able to measure the voltage coming out of the fuel pump relay because, well, I'm not sure where it is! My repair manual says it's in a power distribution box in the engine compartment on the driver's side but I'll be darned if I can't find it...
thanks again for your help!
Eric