A 160 thermostat? Was that what you did? What else?
in addition to the 160* t-stat, program your computer to have the 2 cooling fans come on at the coldest settings possible. i run a 50% distilled water mix with a 50% mix of dex-cool and 2 bottles of redlines water wetter. it very rarely freezes down here. since it get to zero degrees or colder where you live i would just run straight dex-cool with 2 bottles of water wetter. this should get your max temps down to less than 200 degrees. make sure your tune is right and your spark plugs are in good condition as a lean a/f ratio will make your motor run hot too :thumbsup