A few weeks ago I pulled my intake because off my plugs getting fouled. It was warped badly, mostly on the passenger side which is also the side that had the blackest runners(head runners). The driver side head had relatively clean ports but all the valves had the same amount of gunk, and im talkin heavy gunk. Should I pull the heads to clean the valves and chambers or is there another way? is that gunk on the valves greatly effecting horsepower? Theres other concerns but i wont bore you with the details, i just want clean valves.