I'm having an issue with my newly rebuilt Evolution .46NX. I replaced the piston/sleave, connecting rod, and wrist pin. Bearing are fine, carb is clean, ect. I was breaking it in today every thing was going well for the most part. However, it will NOT idle. As soon as the RPM drops to what a normal idle should be it just dies without warning. No hessitation, sputtering, or anything of the sort. After 2 tanks I started to find the sweet spot on the high side and set it 2 clicks richer untill I get more run time out of it. I tried messing with the low speed but that just caused more issues with the idle. So I returned that back to where I had it. It transistions very well from low RPM to high RPM after the engine has been at 1/2 or full throttle for a few seconds, so I know the low speed is good. I've checked for any cracks in the fuel lines (which they are new).

Someone please help me out because every time I tried to come in for a landing and brought the throttle back I was dead sticking it in. I have added a Bison Pitts muffler to it since this engine is now inside of a Stinger instead my old Escapade. It's the muffler made for an OS 46AX but horizon said it would work without issue. I'm using an OS #8 plug and I will try a #6 next time to see if helps. But does anyone have a clue to what could be wrong?