Thanks for the help and sorry for not replying sooner - I've been pretty busy.
I don't know how long the pump sat, only that it was "guaranteed" to work or be rebuildable core.
The car would initially run well at lower RPM with the "new" pump, but would drop off in power and start stumbling in the mid and high end. Letting it idle for a bit would let it be able to rev again.. for a bit. Running from a jar of fuel didn't seem to make much difference, so that rules out a plugged fuel system or failed tank venting, but squeezing the inline priming bulb (which has a check valve) would make the pump spring to life, so I'm sure it's a weak low pressure end... probably stuck vanes?
I've connected everything back to the fuel tank and put a "professional" series Facet/Purolator lift pump in, figuring that low PSI would only extend the life of the pump, and it runs better than ever in the low to mid range but still seems to starve. Running in 2nd gear, it starts to stumble about 3/4 of the way to the 2nd shift point and won't go any faster. Shifting to 3rd, I can get 2/3 of the way up.
There isn't air in the first 3 return lines now, but the cyl 4 return line (between 3 and 4) still bubbles slowly but steadily from the #4 injector when the car refuses to rev higher. I'm told that this could be a sticky injector or bad timing causing air to be forced through a partially open injector. I'm pretty sure the timing isn't off by much and squeezing the priming bulb prevents the bubbles, so I think it must still be starving.
So, on to the ATF I suppose.