while doing all the other stuff that you had problems with did you get the battery load tested and make sure your battery cables are good? Check the fusible link box for something loose there. Be sure you have a good ground from the battery to the frame and are not attempting to ground thru the starter as that isn't a reliable way to ground and Z's with low voltage have all sorts of gremlins. could be a faulty igntion switch. only way to eliminate fuel as an issue is to get a fuel pressure gage and mount it in the cockpit so you can see if anything is awry there. possible something wrong in the fuel pump relay circuit.