Ok, give me an example where McCain has said one thing but done another. Give me an example of where he has lied. I'm not claiming he's perfect, and you may indeed be able to find some flaws. But in general, I see him as one of our more principled politicians.
It isn't that McCain's a liar. It's that's he's seriously unstable.
Simply doing what you said you would do isn't necessarily principled behavior.
I am not accusing him of lying, so please don't think I am. I could give you several examples, but what would that prove? Here is one small example since you asked. Lately McCain is making himself out to be a good friend of the religious right when clearly he was not in the past. He knows he needs them to win, so it's understandable he would shift gears now when he needs them. I agree, McCain is a good man, and if there were only two choices of who I could vote for between Rudy and McCain, I'd vote for McCain.