BTW, the most common issue on these engines is oil buildup in the intake manifold. High RPM driving will vaporize the oil and then its sucked into the intake and can cause carbon fouling of the plugs or buildup in the intake runners and on the injectors. A popular tuneup involves the intake of Seafoam additive through the intake manifold to rid the carbon. I wash mine with nitrous and fuel through a plate nitrous kit.