Is this semi-bluff +EV?

[mayesie]

No offense, but the 4th st. check-raise was pretty weak.

Why do you put him on a King? Although a King is possible, so is an Ace or a Middle Pocket Pair (99-77)

I think you should be going for a cheap showdown at the River because there's a chance you're best (uncertain as it may be). The villain looks like he has a high WTSD%, making it unlikely to induce a fold.