Your idle bypass may be either too high, rich, or too low, lean, or your idle adjustment may be too low, not enough air past the shutters. I don't run an idle bypass, I just set the barrel valve a little rich, and run idle off of it, sometimes the idle pressure is too low from the pump, for the bypass to be able to control it, especially with a poppet type bypass, and yes, I know, it will be rich when you get back in the throttle, so I just trail brake it a bit, and add a little throttle, and it works OK, then it is clear when you pick up the throttle on a restart, or if you get a bit held up in a turn. Bob