[chief444]

MP3 is calling with something...likely one of the two remaining A's. CO would raise a 4 here as well on the flop and there are two 4's left. Plus CO posted and a 4 is just as likely as an ace. So you should be less than 50% sure. And since some aces do beat you probably more like 30% you're chopping. Also consider that CO is more likely to raise the flop with a 4 than a weak ace. The flop raise itself makes a 4 more likely. So all things considered I think about 75% of the time you're toast here and even calling down is questionable, IMO.

Meta-game doesn't really apply as much online and certainly not at Party 2/4.

You have little to no chance of getting a typical 2/4 player to lay down an ace...especially if he's raising the flop with it.