[J. Stew]

i don't think many people are going to advocate a fold here. your hand is disguised, K9 isn't really in his range, 99 shouldn't be there given the read, 89 probably would've raised turn and dumped the flop unless he made a loose call, basically if he has a nine your read isn't entirely accurate or he got out of line a little bit.

if you think maybe he made a loose call on the flop, picked up a draw on the turn and hit the river, would only bet the river with a straight, and would never try a different line with two pair or a set then folding might be good.

that doesn't help much but i think you need to be playing A+ poker with an above average to professional read to lay this down.