I am having some problems with my OS 46 FX and GMS 47 and I think the problem is me. They both start ok and run and transition pretty good on the ground. But when they are both in the air, they seem to "sputter" between about 20% and 80% throttle. Above or below those ranges and they are both fine. I am using 10% fuel with 18% oil and varying props (which does not help or hurt). I am thinking the problem is adjustment since they are both doing it. Do engines act differently on the ground than they do in the air? Any ideas? Thanks in advance for any assistance.