Hesitation off of idle can be caused by electrical, accelerator pump and a little known idle passage way. This video is about that passage way and how it works.
Rough Idle
This can be caused by several things, but there is one item often missed by the rebuilder and that is the idle tube. These are very small passages and get clogged easily with ethanol residue. Use thin wire to clean out the passages completely. Blow out with compressed air. A whistle with air will indicate a clean passage.
Idle Adjustment
If by chance you have a hot idle compensator and you are adjusting the idle mixture be sure the compensator is closed by pressing down with your finger. The hot idle compensator is located on the primary side of the float bowl and looks like a bi metal flap.