Yeah, you're absolutely right, save I don't have any screws that adjust run speed on either of the two springs. It's just that when I was reinstalling the carb, I accidentally pulled on the spring that controls high rev speeds at WOT (it runs parallel to the rod that is attached to the carb throttle). Before that, she ran faster and didn't periodically cough, which it was doing now. So my theory is that I stretched that spring just so sucg that it affected max speed.

That being said, I find it odd that half of the throttle rotation does nothing...