Ever been a hair from a lower second and cant get it ?

My brothers 440 dart had that stumble for a second right after launch when it launched hard. We figured like you did that it may be exposing the rear main jets as the fuel sloshed back. We raised the rear float a little and the stumble went away, leading us to believe we were correct. The easiest way for you to prove it is do as we did, raise the rear float. Also, a lot of great info in this thread, and weight loss goes a long way!