two questions...first and most importantly, when I have the motor revved to about 10000 rpm and cut the throttle to idle, the motor goes down to idle then "surges" for about 5 seconds up to 3500 rpm and then back to idle where it stays. I can only assume that my mixtures are incorrect. To the question, which one and is it too lean or rich?

Second question, I've got about a gallon and a half of fuel through my motor which is a saito 72, I have a 13x6 prop with omega 4 stroke fuel and an os plug. I can only get a reliable idle down to 2400, after that sometimes it stays running and sometimes not. Is that normal break-in stuff. I hear people running these motors down to 1600 with a reliable idle.

Or maybe one answer will answer both of my questions. hmmm