Who did the engine John and installation of the peripherals?
Options:
Weak fuel delivery pump when hot, plus leaking cold start valves, plus failed injector warm-up thermostat, plus trans vacuum leak, jammed idle screw when someone touched it while running, jammed rack... so many options with any combination occurring together. I suspect it should start, run, and idle even if all of the fuel delivery is set back to the original specs - just a little harder to start and a lean idle, but then lean off under load. Then, blocked fuel return hose etc..
regards
Michael