I put it into gear and it dies.

Sounds like the "run" circuit either has an intermittent or the switch itself

IT IS important to understand how this circuit works:

RUN--(dark blue) When the key is in "run" the key supplies 12V to one end of the ballast and that line is also branched off to feed the VR and depending on year, "couple of other things.

START--(yellow) Hot ONLY in start, it ONLY goes one place---to the start relay

BYPASS--(usually brown)--this is also hot in "start" BUT IS A different set of switch contacts....it goes to the coil+ end of the ballast and supplies full battery power to the coil in "start."

So if you do not have power in 'run' this goes through the bulkhead, to the ignition switch. Wiggle the bulkhead, check for power, pull the key connector or key switch out and check there. Wiggle stuff. Work the connectors in/ out and check for "tightness"