I Have ahd problems with it from day 1. Now Ive switched fuels and problem is WAYYYY WORSE!

When I start it up for the first flight of the day everything seems fine, and first flight is uneventful. Then....Second flight Ill be 1/8-1/4 stick throttle and then hit the gas and it stumbles and 90% of the time it will die and dead stick landing here I come. I was using 10-15% Omega fuel, now Im running 25% PowerMaster. Ive got another 46FX and it runs like a dream, but this one is starting to erk me off!
Is it the low end or the high end I need to adjust?