KK against chip leader

[private joker]

Middle stages of a live MTT... 2 tables left and I'm one of the bigger stacks with t2350 (after posting). Blinds are 50/100.

Two loose, bad players limp in EP and MP. An aggressive player who is also the chip leader at the table and has me covered by a significant amount raises to t300 in the CO.

Folded to me in the BB with K[img]/images/graemlins/heart.gif[/img] K[img]/images/graemlins/spade.gif[/img]. I make it t1000 to go. Limpers fold, and the CO calls.

Flop comes down A[img]/images/graemlins/club.gif[/img] Q[img]/images/graemlins/spade.gif[/img] 7[img]/images/graemlins/heart.gif[/img].

What's my line? Check-folding seems weak, allowing any hand to bet me out. But what is he raising and calling t1000 with that's not QQ or a big A? Should I make a feeler bet and fold to a raise?

And how's my preflop?