top pair top kicker?

[lotus776]

Alright, final table of a MTT and I am runner up ($12,200)to the chip leader ($15,300)blinds are 300/600/50. I catch AKo and am in M+2 position. The action fold to me and I raise 3X the BB. The CO calls and so do both of the blinds. The cut off is the chip leader and the blinds are mid-stacked. The flop comes Ks Qh 4c, rainbow board sounds good. The small checks and the big min. bets. I raise him to 3X. The CO calls. the small folds and the BB calls. The next card is 5h. The BB checks and I bet 1/2 the pot. The CO calls and the BB folds. The river is 8d and I bet 1/2 the pot again and the CO raises me all-in...I am pot committed. What would you do?