Is it possible the 15.75x13 prop is not giving enough flywheel action to keep the engine running at low rpm? Are there any other 3 blade props you would recommend? I can't go much larger than 16 inch diameter.. I got the max RPM up to 5000, and flew my airplane for the first time. The plane is designed for a 90-120 4-stroke the RCV just barely got it off the ground.