That air damn you busted off helps run cold air to the rad.. Have you replaced it yet? Could be a problem.. Also, try addin' a bottle of Redline synthetic rad fluid.. I love the stuff.. Its called Water Wetter.. You can add it to antifreeze water mix.. But its supposed to run your engine the coolest with straight water only.. *which is not recomended for street and daily drivers..
Also, You shouldnt run a 160 degree thermostat on a stock prom.. Get an aftermarket chip.. Thermomaster by hypertech is probably one of the best..