I used a can of Berryman's Chem Tool which usually cleans her right out, but it didn't seem to really improve/worsen it at all. If I recall correctly this started occurring shortly after I "cleaned" the ISC, I dont know if that would mean anything to anyone. I'm going to pull as many plugs as I can reach tomorrow and check to see if any are fouled, but its still runnings smoothly so I kind of doubt it.