Harms Rebuilt '71 Thermoquad - Wondering Idle, Stalls when Put in Gear

You have two different brands of carbs doing the same thing: varying idle speed.

Something not right with only 11" of vac. It is low, for whatever reason. It is probably causing havoc with the PCV valve. I would disconnect the PCV hose at the carb, & plug the carb port. See if you can then set the idle.