The only thing that can cause this is a warped head or deck level .......cracked block or head .......head been shaved too far causing too high compresion but plugs should be burning up too ........wrong head gasket >?
I have had this problem before but above has fixed it ...felpro blue headgaskets usually fix it with the correct torque ......new headbolts also lubing them so ya can get correct tourqe but have in many cases run the headbolts down with a 3/8 air ratchet and then take a 1/2 drive and run them down with never having a problem ......ya got a parts problem sounds like if the head and block ok ...
Did you find why the headgasket blew the first time >??????????????????????????
bg
August 2009