I think you might be experiencing what is commonly called a tip-in hesitation.
This is often caused by the primary throttle blades being too far down on the transfer slot, which is a typical occurrence when trying to run too much idle-timing for the carb. It just takes too long for the transfers to come up to speed.
The simple solution is to increase the idle speed,to move the butterflies up the slots,and then take out some idle-timing to slow it back down. Works for me every time.