Initial instinct was fold, and i just typed a great big post about why it"s a fold based on there being nothing out there that we can beat when he check/shoves the river....... unless it"s a stone cold bluff.
But then I re-read the post. We are only losing to KK/KQ/QQ/QT and if he had any of these hands, would he really check the river after we had just appeared to give up on the turn when checking behind? Surely, after we have checked behind on the turn, he has to lead the river to gain value and to avoid the risk that we just check back again. So, for that reason, I suspect a bluff rather than the nuts.
Call.
No, fold.
Oh sod it, call.
Definitely fold.
Eyes closed. Big sigh. Call.