first thing, when she turns the wheel either direction, it makes a clicking noise.... it's really annoying... she took it to firestone about a month ago, they replaced her tie-rods and it fixed it for about 3 weeks.
Take it back and say it was in and it wasn't fixed. I'm not sure about their warrenty but you could try that route first. But the clicking could be from a CV joint too.
second, her car's idle keeps on dipping around. She's throwing an O2 sensor code. Would that make her car's idle go all over the place? Her car also runs pretty darn rough... which I would blame on the O2. I thought about just unplugging the O2 and let it run in "limp mode" to see if would fix the idle.... any thoughts?
Yes, it could make the car do that. You should also be getting worse gas mileage. If it's giving you that code then just replace it. It's not complicated and you can always take the part back if that's not the problem.