for richer or leaner

Hello all!
I have been palyin with a 406 this summer.
My question is when I accelerate and I shift from 1st to 2nd and 2nd to 3rd I get this surge like miss but if i put my foot in it alil more it goes away is this a sign of lean condition or rich.
it is a mech. secondary 750 mighty demon carb other than that the plugs are a lil browner than i like but they are burning alright.
My timing is set at 20 deg. base 34 total vacuum advance not hooked up it runs thew best at these settings

Are you "tipping" into the 4 barrel when this happens....the transition from the primary to secondaries can do this...

edelbrock carbs are bad for this.... I suspect this maybe your problem to...If you let up a little or push down a little more and it goes away you'll know for sure...