Low straight gets there, now what?

[Ace0fSpades]

Villain is running 34/4/3.5 and is pretty donkish. He is limp/calling preflop a lot with god knows what, so I've been overlimping him and isolating him quite a bit, the table doesn't seem to even try to stop me despite my relatively LAG image. I'm unsure of my turn line and then very unsure about my river line, all thoughts please:

Full Tilt Poker, $0.50/$1 NL Hold'em Cash Game, 5 Players
LegoPoker Hand History Converter

Hero (BTN): $110.90
SB: $100.15
BB: $100.75
UTG: $245.70
CO: $102.55

Pre-Flop: 3[img]/images/graemlins/diamond.gif[/img] 4[img]/images/graemlins/diamond.gif[/img] dealt to Hero (BTN)
UTG calls $1, CO folds, <font color="red">Hero raises to $4.50</font>(lol, standard), 2 folds, UTG calls $3.50

Flop: ($10.50) 5[img]/images/graemlins/club.gif[/img] 7[img]/images/graemlins/heart.gif[/img] 3[img]/images/graemlins/spade.gif[/img] (2 Players)
UTG checks, <font color="red">Hero bets $8</font>, UTG calls $8

Turn: ($26.50) 6[img]/images/graemlins/spade.gif[/img] (2 Players)
<font color="red">UTG bets $15</font>, Hero calls $15(?)

River: ($56.50) 9[img]/images/graemlins/diamond.gif[/img] (2 Players)
<font color="red">UTG bets $35</font>, Hero?

[MasterLJ]

this is chop/chop at best. An 8 is absolutely in his range... raise turn next time. $50+ sounds good.

[KhalynYohrk]

Questionable, I think I would make the call though. Its a reasonable price and only the 8 beats you. He might have two pair and think its the nuts.