turn the idle mixture screws in on all four corners to 1/4 to 1/2 turn out from all the way in and look at your AFR I have had to do that on several Dominators and other carbs. to get them to idle clean and drive clean at low RPM As already said a hotter plug and bigger idle and intermediate bleeds will help also, change one thing at at time until the motor is happy sometimes you have to change the main jest also