A common pair vs draw situation

[KdoubleK]

Ok I hope this warrants response. Live 20-40, laggish but sensible player open raises from MP1, button calls, I call from BB with 88, 3 to the flop. Flop is 9 [img]/images/graemlins/club.gif[/img]6 [img]/images/graemlins/diamond.gif[/img]4 [img]/images/graemlins/club.gif[/img]. I lead hoping to get raised, MP1 obliges, button folds, I 3 bet, raiser 4 bets, I call. Turn is 6 [img]/images/graemlins/spade.gif[/img]. I check, he checks. River is blank and I instabet. He ponders then folds A [img]/images/graemlins/club.gif[/img]K [img]/images/graemlins/club.gif[/img] face up. My question is, in situations such as these where I might be against a draw on the turn but could also be against a bigger pair, is it correct to always lead out on a blank? There's no question that I give up a lot by allowing a free card, but if I lead and get raised by a player whos capable of pushing a draw what then?