Switch back to 10% nitro and see if it runs okay. If not, then you know it's not the fuel and that there must be something else wrong (like the aforementioned crud in the needle). I was lucky enough to purchase a bottle of fuel that was bad. I had all sorts of trouble with the engine and changed everything I could think of. Finally I bought some different fuel and that cleared it right up. The fuel probably isn't the problem, but it doesn't hurt to check.

Kerry