I guess you have a mild version of what I had - your idle jet is running slightly too lean.
(I'll apologise to the engine techs now for the "non tech" way I write this)
Your carb has essentially got two ways to get the fuel into the air stream - the idle jet (adjustable) and the main jet(s), which are fixed. As you open the throttle the pressures (or more accurately, vaccum) inside the carb cause the fuel to flow through the main jet at an appropiriate flow rate. Problem is if you whack the throttle open too quickly the initial slug of fuel can't accelerate out the main jet quick enough, so it stalls.
By making the idle mix slightly richer (slighty more fuel per volume of air) you have a "fuel cushion" to get you through that initial movement of the main jet fuel.
I had a Suz 25, a Yam 55 and my Merc all suffered this when I up pitched the props (and so put slightly more load on the engine at idle).
The way to test if that's your problem - bang the throttle open, and as you do so, blip the choke. (That gives you an extra wee slug of fuel when you need it). If it takes off like a scalded cat, richen your idle mix by about 1/8 of a turn* on each carb.
* 1/8 turn is a guess!