Should I donk my flopped flush draw?

[Buck Naked]

I'm not sure about any street here. How would you have played it?

BB is 38/10 having showed some aggression post flop over ~100 hands. MP is loose and passive.

PokerStars 1/2 Hold'em (5 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: 2+2 Forums)

Preflop: Hero is SB with 9[img]/images/graemlins/heart.gif[/img], 8[img]/images/graemlins/heart.gif[/img].
<font color="#666666">1 fold</font>, MP calls, <font color="#666666">1 fold</font>, Hero completes, BB checks.

Flop: (3 SB) 4[img]/images/graemlins/heart.gif[/img], Q[img]/images/graemlins/diamond.gif[/img], K[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(3 players)</font>
Hero checks, BB checks, MP checks.

Turn: (1.50 BB) 8[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(3 players)</font>
<font color="#CC3333">Hero bets</font>, BB folds, MP calls.

River: (3.50 BB) 7[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(2 players)</font>
Hero checks, MP checks.

Final Pot: 3.50 BB