Badly Played "combo" Draw - 2-5NL

[DrClaw]

2-5 NL 300cap 8-handed

BB (hero - 450) = 9d4d
MP1 (weak passive - 700)
MP3 (lagtard - covers)

MP3 is a very laggy, very aggressive player who will get more than 100BB in with one pair or a flush draw, but he will do the betting and raising, and will rarely call off with those hands. MP1 is a new player who has shown no aggression so far but has picked up a few big hands which he has slowplayed to the river. He's also been bluffed off a few pairs.

Preflop: I'm in the BB with 9d4d and get a free play behind 5 limpers including MP1 and MP3.

Flop: (30) Ad Td 9h
UTG checks, MP1 bets 15, MP3 calls 15, 2 folds, hero raises to 65, UTG folds, MP1 calls 50, MP3 raises to 175, ... hero?

MP3 can do some pretty unusual things, but with the 2 draws out there I believe that he would have raised a really huge hand after the initial MP1 bet to protect himself, he can be pretty random though. As I'm debating with my pair+FD, I see MP1 playing with a tall stack of $5 chips. Sometimes that means that he doesn't want me to come back over the top and he'll fold if I do, but in this case I doubt it, because if he's calling the 175 he's calling my push. I'm worried that either MP3 or MP1 could decided to go all the way with a bigger flush draw, or even the chance that MP1 is playing top 2 pair, which means I'm drawing to only flush outs. Do I have to lay this down, and is there a better way to get the pot than how I've played it here? (i.e. bet/3bet)