Car stalls after Warm

Have 1970 340 Duster Auto running a Carter carb mild cam 10:! Comp car runs great for about 4 miles then will stall out if i put in neutral it will not stall if i pump gas pedal in drive it will stay running
i know its a fuel issue just cant pin point, new fuel filter fuel lines are all new front to back, Fuel lines are routed per factor. I was thinking vapour lock but i think its something else. I drove 20 miles a couple weeks ago
and thats when it started after the 20 miles. now its after a couple miles. Any ideas would be appreciated. Thks