Slant six 1920 stall

Hello,
I have a 225 slant in a 1969 Plymouth Valiant four door. I am having an issue where when I have the car in gear it has no issue Idling then after about a minute it sputters and stalls killing the engine. Upon watching this the fuel evaporates and floods the vent and boils in the throat of the carburetor. My exhaust butterfly valve moves freely. I have rebuilt the carburetor using a kit replaced all rubber lines and checked for vaccine leaks. Chokes opens and closes when it should. I have not checked the valve lash or points. Car is manual brakes and steering auto transmission. The fuel lines are not hot and the pump seems to be good filling the lines and providing a good shot of fuel when driving. Only happens when the gas is not pressed.