Pull the carb trumpet, slap a piece of tape on the cowl, and test.... Or experiment turning the trumpet so the angle is pointing various directions, and test to see if one position behaves better. It also could be airflow over the reference pressure hole in your carb plate. routing this into a non-turbulent area inside the fuse could resolve this.

I personally have had no issues with carb trumpets poking out the cowl, and though the position of the angle made a slight difference, it was nothing worth changing permanently. My money is on the tune of the engine, and the reference pressure modification.