Sorry for your loss, a good Q-jet mechanic tough to find. They are easy to work on. Sounds like dirt in one of the idle circuits. Try some carb cleaner with a spray tube on it. Look in the primary side ( Front of carb ) and you will see some small ports. Spray down them to try and clean out what ever is in there.
The engine creates vacuum that pulls air and fuel through the carburator passages. If the air vent is plugged all it pulls is fuel. This would explain the rich condition you are having. Joe
