hi there, im a little bit lost with this on my 5.0 swap into my 68 mustang, i got most of it wired up temporarily, but didnt know where the black with white stripe wire should go, that came from the green square connector in the kick panel of the 88 mustang.
It goes to both the NGS and the clutch switch, then on to pin 30.
when i turned on the ignition, the fuel pump relay energized for a second, then switched off.. giving this black-white wire 12v turns on the fuel pump again
Don't do that.
Powering unknown pins for fun is not always safe for electronics. Anyway, ON then OFF without cranking is correct. The ECM powers the fuel pump for a second or two when keyed to ON (not START) in order to prime and pre-pressurize the fuel system. It then stops the fuel pump until it 'sees' ignition trigger pulses (meaning an engine turning and trying to run) and turns the pump on again. As long as the ECM sees trigger events, the pump runs. Turn the key OFF or stall the engine and the trigger signals stop, and so then does the pump.
i also have confusing information regarding the red-blue stripe wire, - i suspect though, this is hot in start only and connects to the starter relay, tfi, and the coil for start power only, but no power if the t5 is in gear and clutch is out. so that would also connect to the ground side of the NGS (i have no clutch switch) ?
Right, it gives a cranking signal to the starter relay (solenoid), and signals other stuff that you're cranking the engine.
so to the + side of the NGS what do i need to use? does that go straight to pin30 on the computer?
Yep. With an automatic trans, it doesn't care, but with a manual, the ECM must juggle idle speeds differently. So, in order to prevent stalling when you suddenly push teh clutch in or pop out of gear, the ECM sees the 'neutral' condition and compensates with idle air valve and fuel. It is equivalent in function to the dashpot used on carbs.