raise preflop. I think this is a classic case of reverse implied odds. Even if you're ahead, there are several cards that will cost you the pot. The fact that MP3 wakes up after a bet and a call means that he's either got the flush, the naked A or two pair of some sort. A set would have most certainly raised the flop. He's probalby got the flush, and I think you can go ahead and fold here.