Fox plugs are OK, but not the idle bar plug. Fox Gold Post should work fine. But since Tower doesn't carry them not many shops do. I like the Enya #3 when having problems. You need a hotter plug when using 5% nitro, which an Enya #3 is. The OS #8 is fine if using 10% or 15% nitro. I think the combination of low nitro and a fairly cold plug is your problem.