Give it 10* btdc and try increasing idle mixture. My LeMans does the same thing, because the idle circuits in the Qjet I'm using are emissions calibrated and won't provide enough fuel. Also check for fuel slosh in fuel bowl, choke adjustment, check manifold vacuum.

good luck

chip

Preaching the Hot Rod Gospel according to the 4-stroke apostles:

Suck, Squish, Fire and Fumes