If MP3 is a decent tag, there's very few hands that he's 3-betting preflop: AA-TT, AK, AQ, AJs, KQs, possibly something like 99 if he's capable of that type of iso-raise.

MP3s bet on the flop doesn't tell you much. However, when MP3 raises the turn after the donk bet and a call, it's unlikely that he's raising two players with KK-TT or KQs (I don't think he raises the turn with KQ of diamonds). I can't imagine him raising the turn with anything worse than aces up. If he has you outkicked, you have three outs (the 3 remaining Js) and another three (the fourth A and the other 2 9s) to a split

The only hands I can see MP3 having that aren't ahead of you are AJs and ATs. Even if he has one of those hands, you're vulnerable to a third 9 or a K or Q counterfeiting your kicker on the river. There's also the less likely case that he has a nut flush draw, in which case you have to dodge several more cards on the river.

I call the turn and may consider folding the river UI if I'm EXTREMELY confident in my "decent TAG" read; however, that pot is probably too big to fold for one more bet.