Hmmm. Let me a guess here too. Because without more specifics that's what we all are doing is guessing based on practical experiences. So here's mine . I have seen 2 DLE 20's with mystery carb issues that required new carbs ,that's guess 1 . Guess 2 is replace the DLE spark plug with a real CM6 plug , we've all seen that issue . Guess 3 , the prop isn't balance and either the vibration is causing the ignition pickup sensor go erratic at high speed or vibration is killing the ignition switch and it drops/ reduces voltage to the ignition . Those are about the craziest guesses I've got , but just because they're crazy doesn't make them any less plausible... But seriously give us much more detail on battery , voltages , props used . How old the fuel is . Moon phase etc.