Depending on the size of your raise and the size of your stacks relative to the blinds, calling there with AQ might be good. The way you describe it, though, it sounds like you and your opponent were both very deep stacked. Then it's a big mistake as you're getting worse pot odds
on a call and your opponent's shoving range should be much tighter.
I have some problems in the late pre-final table stages of tourneys as well. Generally what happens is I do build a stack, but then my steal or loose raises start getting picked off over and over. You usually have to win two out of three steals to break even, and I'm sure it's not working that often. I've tried playing tight, but that usually just dwindles my stack down to very little. I've tried raising from earlier positions so that it doesn't look like a steal, but that doesn't seem to work any better. The one thing I have had some success with is trying to be the one picking off the steals rather than stealing in the first place. I like that approach a little better, because you're effectively heads up and your villain has already acted, so you can get a read before deciding. Also, you're the one making the final action, so you can't get bluffed off the hand by a super aggro opponent.
Other than that, getting good hands and winning coin flips is a very good idea. Honestly, every time I've won a >50 player multi, I've gotten a rush of hands heading into the final table. Having a big stack early is pretty much meaningless except it gives you more time to hit your rush.