Tough 3/6 hand or easy money?

[hellite]

Party Poker 3/6 Hold'em (10 handed) converter

Preflop: Hero is BB with 5[img]/images/graemlins/club.gif[/img], 4[img]/images/graemlins/club.gif[/img].
<font color="#666666">2 folds</font>, <font color="#CC3333">UTG+2 raises</font>, MP1 calls, MP2 calls, <font color="#666666">4 folds</font>, Hero calls.

UTG+2 and MP1 are straight maniacs - very loose/aggressive; They have both been raising and reraising each other with weak hands. MP3 is very tight and aggressive.

Flop: (8.33 SB) T[img]/images/graemlins/heart.gif[/img], 2[img]/images/graemlins/spade.gif[/img], 3[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(4 players)</font>
<font color="#CC3333">Hero bets</font>, UTG+2 calls, MP1 calls, MP2 calls.

I was expecting to get raised here but...

Turn: (6.16 BB) 2[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(4 players)</font>
<font color="#CC3333">Hero bets</font>, UTG+2 folds, MP1 folds, <font color="#CC3333">MP2 raises</font>, <font color="#CC3333">Hero 3-bets</font>, MP2 calls.

This was a little confusing; MP2 simply called on the flop after two maniacs called in front of him; then he pops on the turn? What gives? I put him on a small pair or overs (he possibly picked up a flush draw on the turn)and sent one back his way. Given his numbers, I would have expected him to either 3-bet preflop or raise the flop with any top rank hand. Either way, I figured the only way I could win this pot (if no A or 6 hits the board) is to 3 bet.
Though I currently have no hand, I do have 6 clean outs to the nuts. My plan for the river is to bet any card and fold to a raise. Any thoughts?