50nl AQ oop vs unkown

[Das Budrick]

looking for a line check, would you fold pf, how is my river play?

villain is unknown
Full Tilt No-Limit Hold'em, $0.50 BB (8 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: 2+2 Forums)

saw flop|<font color="#C00000">saw showdown</font>

MP1 ($59.75)
<font color="#C00000">MP2 ($47.95)</font>
CO ($10.35)
Button ($48.25)
SB ($54.25)
BB ($34.40)
UTG ($46.20)
<font color="#C00000">Hero ($51.55)</font>

Preflop: Hero is UTG+1 with A[img]/images/graemlins/club.gif[/img], Q[img]/images/graemlins/diamond.gif[/img].
UTG calls $0.50, <font color="#CC3333">Hero raises to $2.5</font>, <font color="#666666">1 fold</font>, MP2 calls $2.50, CO calls $2.50, <font color="#666666">3 folds</font>, UTG calls $2.

Flop: ($10.75) 4[img]/images/graemlins/heart.gif[/img], A[img]/images/graemlins/spade.gif[/img], 4[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(4 players)</font>
UTG checks, <font color="#CC3333">Hero bets $7</font>, MP2 calls $7, CO folds, UTG folds.

Turn: ($24.75) K[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(2 players)</font>
Hero checks, MP2 checks.

River: ($24.75) 3[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">Hero bets $18</font>, <font color="#CC3333">MP2 raises to $36</font>, Hero calls $18.

Final Pot: $96.75