Sounds like you got that covered.Maybe you are experiencing Spark Blowout.it is more of a problem with turbo cars but it does happen on NA cars as well.If it still does it with new plugs,set your old plugs .010 tighter than you have been and see what that it does,a lot of the turbo guys are running .020-.028 gap...
Google Spark Blowout and on UTUBE and see if that is what you are experiencing.
Good luck.
