Car is smoking white from engine but it only when back to idle

I have a 1998 mustang with a roots supercharger I recently fixed a coolant leak on one of the radiator hoses. even after that white smoke continues to come out from under the hood I do not believe it is a headgasket. Because I still have proper compression in all of my cylinder heads, and there is no oil/coolant mix at all on the inside of the oil cap. Have been trying to find out what it is for about two weeks. It comes from the area directly behind my headers. Any ideas?