Just so you know, turning on your a/c DOES stress your alternator. I'm too lazy to type it all out, but yea, that a/c is probably not helping alot. Turn up your idle screw so that your car doesnt die, it will help and keep the car on. Take it easy. Peace

P.S. and no your 02 sensor won't make your idle die out, it'll cause more sputtering symptoms of that sort i would think.