I already searched and read alot of the same CEL code, my problem seems to be a little different....out of the blue I get a p0304 code, I pulled the #4 plug and the electrode is mostly missing, it looks like it burned/melted off,all the others looked good,(plugs were only about 4 months old)after a new set of plugs its good for a few weeks...then....p0304 is back....the plug looks good...the wires were new before the burned plug,(new MSD's)...Im going to re-route the wires according to the TSB.....but why the burned plug only on #4? pre-ignition on one cylinder only? vacuum leaks? is there any hoses or any other sources of vacuum leaks that would relate to that one cylinder only?

thanks in advance

 

Do a compression check.... Seafoam the engine. (thru the brake booster hose.) Swap the #4 injector with #2, see if the problem moves.