Ok, got the O2 sensor changed, new fuel cap and no cel. Runs great except for one small problem.

I hear a slight ringing sound coming from the the serpentine belt, power steering, timing belt system. I believe its when the ac is on. So, could it be some bearings going out. I dont believe its a belt but maybe a pulley that might be going bad as the bearings I believe are ringing.

Any ideas?

 

Check the belt cover for rubbing... definately don't want that.