Getting the injectors clean is defiantly worth it I think, and you can either have them just cleaned, or cleaned and flow tested.
RC injectors in Socal will clean and flow test them for $25 an injector.
I feel like a new fuel pump wouldn't hurt either, but you could probably just try and guy a used one that works off a known member. I sold mine to my friend for like $20, but then again he bought like $200 of parts from me to get his ZX running.
My fuel pressure is set to 35ish. I had it down to 30 though when I was doing cross country. Saved gas.
Don't remember if you said you changed all the rubber gas lines and filters, but you should do that too. And how is the tank? Do you know if its rusty inside?
As for the throttle body being black, that's normal for an old car. The PVC system is routed to the throttle body so if the engine is old it probably has some blow by or oil getting past things. If its a lot of oil that's bad (like a steady drip). Does it smell like gas or oil more?