1966 300, 383, total rebuild. Stalling

Sonim at my wits end. Not sure if I have a fuel, vacuum, or power issue. Car was running fine, perfect actually. Now suddenly it wants to constantly stall. It will idle in park and neutral, goes into gear and it wants to stall, sometimes it immediately dies. Sometimes when I press the brake (all drums) it dies. Sometimes when I push the gas at a red-light it dies. Once it running at a higher speed it runs perfect. I've adjusted the timing, the idle screw. If i run the timing advanced...

1966 300, 383, total rebuild. Stalling
Author: Bryon Mason