Trail..... how much fuel do you have through your engine? i would not mess with stuff like changine compression, cuz they make the engines with that much compression for a reason. when you increase the compression that much (it dosent seam like alot but it is) you change the timing of the engine. and your engine may be experiencing pre detonation, which is where there is so much compression that the methane ignites by just the compression. that is why when you use extra washers it runs better. oh and also. how long have you had that particular gallon of fuel. because when you open it one of two things will start to happen. 1. the alcahol in the fuel will draw water. 2. the nitro, which is what keeps the alcahol from igniting too early, evaporates.