My MVVS 1.60 gasser also "four strokes" at half throttle with good idle and the top end mix set at best power. If I lean the idle mixture to clear up the midrange then it is too lean to accelerate from idle. I just have just had to live with it. I have it in an 80 inch Hangar 9 P 51 which needs every bit of power the MVVS will deliver...so I just fly around full bore.

Jerry