The fuel foaming was a huge problem on the old Yamaha 570 Exciter snowmobiles back in the day.Vibration/harmonic resonance from the engine caused the fuel to froth.But on those it was when you let off the throttle it went extremely lean.PSI had a special tapered needle that had limited success.A guy came up with weights for the fuel bowl that seemed to cure the problem.I,d be shocked if that was the OP,s problem but I guess anything is possible.I agree with the ones saying to try a different needle.