I bought a new DLE 30 about 60 days ago and have ran about 2 gallons of fuel thru it in the air and I cannot not get the miss or burble out of it at about 4000 rpm's. Idle to 3500 rpm's if fine and top end is great, but mid range studders and burbles in the air. I have tried leaning the needles to the point where there is no transition and then opened 1/16 more and it transitions well. My best needle combo's are 1-3/8 turns Low and 1-5/8 turns High. The engine was ran on 2 tanks of lawn boy @ 32:1 and the went to Bel Ray Hr-1 @ 50:1 with 87 octane gas. This last mixtures still slings alot of fuel/oil residue on bottom of fuse and horizonal stab, just as it did with lawn boy oil and richer needle settings for the first 2 tanks, but not quite as much. I am running a Zoar 18 x 10 prop, NGK CM-6 plug (since New and changed plug after switching oil type and now the porcelan color is cocoa with oil residue inside) on an open (no cowl) Road Runner (high wing)weighing in at about 13 pounds. Also the motor has quit several times upon landing, right after the gear touches down with a little bounce. I am leaning towards a carb problem with the tillison carb, but that is just a quess and I am looking for some professional advice, short of returning the motor for service, which was purchased in the USA thru Valley Veiw. Thanks Bob