A quick check to see if the throttle blade position is about right, without adjusting anything, pull the carb and flip it over and check how much of the Transfer Slot is showing below the throttle blade, it shouldn't be any more than the width, should look like a square, or even a lil less, but no more. If it needs more air that's where holes in the throttle blades are required.
Normally, with the engine running, you should be able to see discharge from the Idle port, and the Transfer slot.
The reason for having the Transfer slot open slightly is it stops any stumbles from happening as the Transfer starts to initiate, its already flowing, so is a seamless change from Idle to Transfer.
Gaskets on the mixture screws? Baseplate Gasket to Body correct?