Getting ready to swap a 5.7 into my 73 Dart Swinger

Ok after banging my head against a wall, mind you i havent gotten the new regulator for corvette yet, and had to fix some wiring. i hit it with a tiny spurt of spray amd boom the damn thing started up and idles and accelerater respomded very well. However it will not start on its own and upon start up it went from 58psi FP to 30psi. Yet it still idled and seemed fine with the pedal. Ran twice to see if it will start on its own it doesnt needed the spray vut all together didnt run for more than a minute.