get a can of starting fluid. use it see if you can get a second start out of it. If so then pretty likely you have a fuel delivery issue. need fuel, fire and air to run. load check your battery and be sure your cables are clean, tight and free of corrosion on both ends. Z's don't like low voltage. you can get the amps to crank but not the voltage to run the electrics (ask my wife about the time I took her for a ride and we couldn't get off the ferry). Get a can of Deoxit by CAIG. clean the connectors for AFM, TPS and ECU with it. you've done so many other things time to be looking at very basic stuff. You say you measured fuel pressure after the regulator which is the totally wrong place. the fuel comes from the pump to the filter then to the fuel ring and then to to the FPR. your gage needs to go between the filter and the fuel ring. You really need to understand the fuel system. try downloading the fsm from xenon and READING IT.