1966 Plymouth Valiant /6 & Holley 1945 carb can only get to idle at 1250rpm. How to get a lower idle without dying?

Hey guys,
I'm a complete dumbass too lol, I'll update this thread soon (actually soon, I got busy with school and work) again but in the meantime here's what's happened so far:
car has been converted to electronic ignition (by previous owner)
leaking about a quart a week (gonna find out where on sunday) get 13-15 mpg on freeway driving
spare 1945 carb looks really rough (rust, corrosion, overall not good)
rebuilt a NOS 1920 but didn't get any fuel flow
will replace vac lines in meantime to try and ascertain if carb or vacuum issue
also weird thing: there's a black wire coming off the ballast resistor that goes to a small nipple on the side of the choke spring. No idea what it does. Any clues?

Thx.