Help with my 1996 civic CX D16Y7 i am receiving tbe codes p0301 through p0304 and i also think p0300 so random miss fires and miss firing in all cylinders. Iv replaced plugs,plug wires, cap and rotor and nothing. Where should i go from here also the cylinder 2 spark plug is black and not firing properly more then the others and the other 3 plugs are not black and sparking properly. Should i replace timing belt and tensioner, and check for vacuum leaks. Me and my father can do this at home hes great with cars. Also he thought maybe a burnt valve in cylinder two. Any ideas experts please!!!? Any thoughts on the cylinder spark plug being black?