One other thing to check is the carburetor base the part that goes into the case. If the pinch bolt is overtightened, it will create a divot in the metal sleeve around the plastic base. If tightened enough, this will separate part of the metal sleeve from the plastic innards. Thus creating air leaks in two spots of the same area.

I'm also assuming this is a newer gx motor? If not, straight up replace the seals.