Will the car start and run if you turn the key on, and jump the starter solenoid to the 12v terminal? If so, it's something in that wire that starts at the ignition, goes thru the mlps, to the starter. You'll have to trace it out. I had a crap anti-theft alarm in the tbird when I got it, and it caused all kind of problems. If they cut the wire in question and added a relay, like mine, that would be your problem. find the relay, and fix the wiring back to factory. Or put a pushbutton rated for at least 5 amps in a wire directly from battery + to the solenoid, and use that to start the car.