Check the underside of the AVS for main well plug leak. Too much time in the carburetor dip can damage the aluminum main well plug on the bottom allowing the fuel to drip out/into the manifold. If it's difficult to drive when cold then there's a miss-adjustment on the choke valve or the thermal bimetallic choke thermostat rod on the passenger side (pictured).

I'm pretty sure the factory correct carburetor base gasket will cover up the main well, but I'm not sure. Old age memory.

A stuck exhaust manifold flap valve (I forget the correct title) located in the passenger side manifold can cause the intake manifold to run too hot and boil the fuel. Make sure the spring loaded valve can open fully and move freely.

BTW, I too have a 1969 RR 383 with a 4615 AVS. Best of luck and we need more pics.