After looking at many of the posts to find some help for my issue, I decided to just join up and see if I could get some help that way. I have a new YS 115 and recently ran it in per the manual and installed it in the plane. After starting and warm-up I got it to fly ok for a short flight and landed after about a minute or two and checked out everything. Restarted and flew a bit longer about 1/4 to 1/2 throttle and the engine died in flight so I landed and checked everything / all looked ok. All subsequent flights ( 6 ) have been deadstick. It usually seems to run up and down once or twice during flight and then die, sometimes after a throttle change. Seems to be ok level only and part throttle only but any high speed + throttle changes will kill it. It was 400 rich of peak last time I ran it. Engine shipped with a bad jam nut and I had to use a light hub, no reply from YS email and several phone attempts are busy. Fuel is VP 20/20, plug is OS- F , 460 elevation, 73 degree f, APC 16x8 pattern. Tac peaks 9xxx- 91xxx k. Engine is a beast other than deadsticks. Thanks for the help.