Oh ok I remember reading this one. Nevermind your problem is a little more than mine. Here is what I would do. I am not sure if this works on car motors but it's what I did with motorcycles when I would jet the bike right and plugs kept fouling and it was running bad.... I would get carb cleaner and spray it around the cylinder head gasket first. I would hold the throttle a low idle steadily and if it sputtered or died I had a leak. Then if I didn't I would move onto another gasket. Try doing that. See what happens.