Rod just reminded me, I believe that vehicles of that era were still using Idle Stop Solenoids. An idle stop solenoid’s job is to allow total closure of the throttle plate to prevent dieseling when the engine is shut off. This was a common problem when operating temps were raised and metering leaned out in the '70s.
If the carn adjustments are made without the solenoid energized you’ll have numerous problems. Idle needs to be set on an energized solenoid. All adjustmenst need to be made with an energized solenoid.
If you don;t have one, than I stand corrected.