Opponent cold-calls then caps preflop

[Joshua]

UTG is 41/30 LAG. MP is 27/15 TAG. (BB is 36/3)

Party Poker 10/20 Hold'em (5 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: 2+2 Forums)

Preflop: Hero is Button with A[img]/images/graemlins/diamond.gif[/img], K[img]/images/graemlins/club.gif[/img].
<font color="#CC3333">UTG raises</font>, MP calls, <font color="#CC3333">Hero 3-bets</font>, <font color="#666666">2 folds</font>, UTG calls, <font color="#CC3333">MP caps</font>, Hero calls, UTG calls.

Flop: (13.50 SB) 7[img]/images/graemlins/diamond.gif[/img], K[img]/images/graemlins/spade.gif[/img], 5[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(3 players)</font>
UTG checks, <font color="#CC3333">MP bets</font>, <font color="#CC3333">Hero raises</font>, UTG folds, <font color="#CC3333">MP 3-bets</font>, Hero calls.

- At what point do I put MP on aces and nothing but aces? Right now or preflop when he cold-called and then capped in a 3-way pot?

- Can/should I get away from my hand if unimproved on further street(s)?