Continue bluff with AQ?

[buhler26]

B&M Casino 3/6 Hold 'em

UTG player is a guy I know to be a decent player, capable of laying down hands.

UTG raises, all folds to me in the SB with AQo. I call.

Flop is 4 [img]/images/graemlins/diamond.gif[/img] 4 [img]/images/graemlins/heart.gif[/img] 7 [img]/images/graemlins/diamond.gif[/img]
I check, he checks.
At this point, I think he's got overcards, as I'm pretty sure he would bet a big pair here. Possibly AJ, AQ, AK.

Turn is K [img]/images/graemlins/club.gif[/img].
I bet trying to represent K, he calls. I think he would have raised AK here.

River is blank.
I bet again, continuing the bluff.. He raises. I fold.

I hate folding the river to one bet like that. Should I have checked and called? Should I have given up the hand on the turn?

[clownshoes]

After he checks the flop I suspect hes got a big PP (possibly 77 if hes a l337 slowplaying type) or is just a wuss with overcards
The K is a very bad card for you as it clearly pairs a lot of hands he couldve been raising. I wouldnt take a stab at it unless you know hes a really weak player. After he calls the turn I would definitely give up on the river.