Thermoquad idle issue

Trying to smooth out my idle, only to find that if I begin to close the primary butterfly slightly the idle begins to run better. I have all new vacuum lines and thick carb gasket.
A vacuum leak cannot be found anywhere. Any suggestions?
you have thin gaskets on both sides of thick 1/4 gasket? the 1/4 " gasket leaked on mine, I use one thin gasket only.