villain was loose/passive with aggression frequency on flop of like 11% over a small sample.

Microbet usually means either
a)FD, probably not A high
b)Weak K
c)total air
in about 33/33/33%, and then throw in the odd "LOLZ I HAVE NUT HAND I MICROBET" but that's pretty rare.

On flop and turn I figure I'm miles ahead of his range but won't get much value from a raise (I'll likely take it down, but oh well)

On river he takes this line with b)100% of the time, and also with a) and c) a lot, especially if the J hit him (reasonable, Loose Passives love J's).

Maybe I should call river? I'm thinking raise turn is good.

PokerStars Pot-Limit Hold'em, $1.00 BB (6 handed) Poker-Stars Converter Tool from FlopTurnRiver.com (Format: FlopTurnRiver)

SB ($99)
BB ($64.60)
UTG ($102.50)
MP ($104.50)
Hero ($124.30)
Button ($98.50)

Preflop: Hero is CO with 9, A.
2 folds, Hero raises to $3, 2 folds, BB calls $2.

Flop: ($6.50) K, 2, 2 (2 players)
BB bets $1, Hero calls $1.

Turn: ($8.50) 4 (2 players)
BB bets $1, Hero calls $1.

River: ($10.50) J (2 players)
BB bets $6, Hero folds.

Final Pot: $10.50