Carb tuning is a lost art and needs to be hands on for tuning, there is a lot to it unlike EFI which controls many things like timing, air/fuel ratio through sensor imput, carb tuning requires a vacuum gauge, timing light, power valves, air bleeds, jets and patience.
Most times a 'sluggish' condition can be timing or timing advance settings, even spark plugs with a big gap or fouled,
I would start by verifying timing, where it advances (this take into consideration that it has a good spark) and you have no vacuum leaks.
if I remember correctly the AVS style carbs use metering rods, are they freely moving and the floats are adjusted correctly.
This is the starting point. There should be a wealth of info on the manufacturer website but it takes into consideration everything else is working correctly.