to find the vacuum leak get a mechanic's stethoscope and listen around, or try spraying it down with carb cleaner and it'll change the way it runs when it gets sucked in.
you should be able to get an injector pig-tail connector from a good parts guy, fixed lots with no problems. use solder and shrink wrap to keep it weather proof.
rusty O2, heat, lots of it. really bad ones i just melt out and chase the threads. worse case you can get a new bung to weld in.
good luck.