[J.R.]

Many lags slow down on the big bet streets without a hand, and in your limited description it seems he fits the bill, pumping draws and odd hands early and then slowing down unless he catches- which doesn't bode well for your one pair hand here. But its too early to tell based on 3 hands.

Anyway, I'd tend to call the river bet with the flush and 4 parts to a straight on board after you capped the turn with a shot at an overcall from the minor lag and no exposure to a 3-bet, although you were there and it could certainly be reasonable to raise against some guys. But I'm pretty sure I wouldn't cap after he 3-bets.

I would play the flop and turn the same given the possible draws and the fact that your turn cap closes the action and this guy doesn't seem to be the type to check-raise (i.e. you can just call a river bet if he leads)