25NL - AK against maniac

[0uTpLaYeD]

I have been playing at 19/16/6 and have been 3betting villian a lot, but only went to flop once with him(I Cbet and he folded). He has been showing down a lot of marginal hands like J9, 76, K8, etc. and he has been winning.

Poker Stars - No Limit Hold'em Cash Game - $0.10/$0.25 Blinds - 6 Players - (LegoPoker Hand History Converter)

SB: $28.45
BB: $36.80
Hero (UTG): $29.25
MP: $29.60
CO: $35.25
BTN: $26.60

Reads: <font color="blue">Villian has been playing at 81/59/2 over ~60 hands.</font>

Preflop: Hero is dealt A[img]/images/graemlins/spade.gif[/img] K[img]/images/graemlins/club.gif[/img] (6 Players)
<font color="red">Hero raises to $1.00</font>, MP folds, CO calls $1.00, 2 folds, BB calls $0.75

Flop: ($3.10) K[img]/images/graemlins/spade.gif[/img] 9[img]/images/graemlins/spade.gif[/img] 8[img]/images/graemlins/heart.gif[/img] (3 Players)
BB checks, <font color="red">Hero bets $2.00</font>, CO folds, <font color="red">BB raises to $4.00</font>, <font color="red">Hero raises to ?

Do we felt this hand? If so, on what street?