Rebuilt 273 won't idle

I can't get my newly restored 1965 Barracuda with a 273 and original 4bbl carb to idle down.
Dropping below ~ 1500 rpm it cuts off. It was built with a mild performance cam, hydraulic lifters, and 318 heads. The heads are ported and polished and the heads are shaved. Advance is set at 10 deg. BTDC. I blew out the carb adjust holes(3) to no avail. The idle screw is turned all of the way in and it won't stay running.
What should I do?