How much would it cost to fix an O2 censor,also sway bar rear and front

What is your question?

i just bought 4 new tires and I don't know if it's the tires but lately I'm noticing the back end of car sways sometimes . While on highway I feel like the wind is blowing car and if I just yank the steeringwheel a little I'd lose control, and that car is usually very heavy and planted while driving