manifold vaccum for vaccum advance ?'s

ok oldmanrick, what other problems could cause this? this is what i am trying to figure out.
the distributer is brand new phased and I just dont know what else it could be? Don says its the engine wanting more fuel at an idle. He said at idle the engine is in a lean situation and needs the fire lit earlier hence the reason for running vaccum advance off of manifold vaccum, and the manifold vaccum theroy makes sense to me... Your going along at 65 miles an hour and have to back off the throttle really quick the manifold vaccum rises and helps burn the fuel that you just waisted by backing off the throttle real fast.
The whole manifold vaccum to run vaccum advance makes sense, i just need to figure out why this is popping at an idle with 14 initial and 8 degrees from the vaccm advance? I have set my idle air mixture screws to the highest vaccum reading to no end, sometimes i dont hear any pops at all.... When its cooler outside i dont hear any popping out the exhaust, only when its real hot outside and the engine is warm. So is that a clue to what it coul be? I have 17 to 18 inches of vaccum at an idle.