I have a 1999 Mazda B4000 with a 4.0. Had the head gaskets replace and now it pings like the devil
. Temp normal replaced plugs and wires no change. MAF was at boarder so replace it no change. Put 93 octane in it 60 % inprovement but still some ping. I should not need 93. No EGR or Knock sensor on this motor. Sounds like a timing problem but what controls it and how can I fix it.