I was told by Proform (actually, Quick Fuel who does Proform's tech work) to set the float level at the center of the sight window. After fighting idle and performance problems, I finally set the float level at the bottom of the sight window and most of the problems disappeared.

My idle was still rough (too rich) and I needed to turn the idle mixture screws almost closed to get a semi-decent idle. Quick Fuel suggested that I try larger idle air bleeds to lean the carb(s) so that I could get more idle mixture screw adjustment. I went from factory .073 idle air bleeds to .075 and it made a huge difference in the idle quality and adjustability.