iconoclast

yes. it is disgusting and the engine is so large that it builds right back up after 10-12k miles. if you take off the intake manifold you will a great deal of build-up which is removed by manually scrubbing the valves or using a media blaster (walnut shells) and then clearing it all out with a seafoam afterwards and then an oil change. you will need new gaskets as well. if you're in there and want to extract a negligible amount of hp you can port polish the IM and gasket match.