you need to play the gap game with any plug till you feel whats seems best. i gaped em at 60 then 55 then 53 then 50.
nothing felt as good as the 104's gaped to 50, did the same drill with both plugs.
yes thats a lot of plug pulling. and it kinda sucks.
either way, unless the plug is cracked i cant see the brand or temp being the misfire.