Misfire #8

06 Durango misfire #8, changed all plugs at 62k,(shouldve done at 30k) and now at 73K I get this misfire, which after I pull the plug it looks like it has splash back from the engine. why did this happen??

something broke? bad plug wire? bad injector? loss of compression? ring failure? valve seal failure? WTF is splash back?

Nothing broken. splash back in regards to plugs happens when you wait to long to change the plugs, when new ones are installed the remains or remaining carbon etc. are "splashed" back to the hot plug(s). Yes I know it sounds wierd but its true fact..anyway got my answers