What does it do when you run premium fuel. I suspect that by milling the head you've upped your compression ratio and few tenths and put yourself into the premium range. The only solution to that is to put a thicker head gasket on to lower the CR.
Sarge43
"00" Tique 2.0L I4 ATX
"98" Mustang 3.8L V6 AT
The reason there's so much ignorance is that those who have it are so eager to share it.
