You are correct, throttle position determines which circuit the carburetor is working in. However, it's difficult - for me anyway - to identify the throttle position at 2,000 RPM.
We have just experienced a cold snap down here in Texas (low 50s F)which has highlighted a lean spot in my carburetion at around 2,000 RPM. And I suspect my throttle slide cut-away is just begining to come into play at that RPM/throttle position. Confirmation anyone?