still sounds like fuel delivery volume problems, and I'd dose it with about two cans of injector cleaner and let it idle for a couple of hours. or blow out the lines. suspect constrictions are fuel pressure regulator, nylon filter on the fuel pickup in the tank, and the screens on top of the injectors, plus maybe some rust/varnish (had this thing sat for a while with the bad pump?) in the lines themselves.

Not responsible for advice not taken...