Stalling Out
Great. Sounded like a vacuum leak, though Holley 1920's often idle lean if the internal metering block gets plugged. Also, check that the "choke pull-off diaphragm" at the top of the carb works. That is critical in getting easy cold starts. The choke should be closed fairly tight when cold and the pull-off should pop it open slightly the second the engine fires. If not, it will run rich and die. Check that the diaphragm holds vacuum.