Rusty pedal boxes are known to have sticky throttles. 76's had the most problems in this area due to poor drainage. I assume the car was or is still in the rust belt. If not, you should check the links at the carb for freedom of motion and look at the return spring if there or not.

On the other hand; having an electrical issue that seams to be related, perhaps one of the under dash/ engine bay wires has gotten entangled in your throttle and pulled thus exposing a short?

I dunno, just a thought. Stranger things have happened.