[einbert]

This is a little bad. I'm surprised to see you lagging it up after you said you would fold ATs from the BB to a CO raise. What gives?

First of all, I would raise PF. It's close of course, but I think it's a raise. In this case it would have defined CO's hand more clearly.

Just call on the flop. You aren't protecting anything, you're most likely beat and have four outs. You have enough to call one bet with your 4 gutshot outs + 1.5 BD Flush outs, but raising here is not smart--especially after UTG has already called CO's bet. You're not taking the pot down here and you're not taking the pot down often enough on the turn to make this worthwhile.

Since you did manage to get it HU on the turn, I don't mind the bet. You can fold to a raise here so betting isn't bad.

On the river, think of CO's possible hands. If he has a J he's calling you down. If he has an A he's probably raising. With a PP >9 he's calling you too. He will never call with anything you beat, and he will call with just about everything that beats you. Check to him. If you have him pegged as an aggressive player who will bluff here with nothing, call his bet. Otherwise fold.