steal question

[savman]

i am normally a ring game player. lately i have been playing multis with moderate success, trying to learn so i can occassionly play some larger buy in ones. First, I have a question about post flop play in party structure tourneys. Primarily I avoid it. I have been playing 30 dollar and less buy in tourneys, and two factors have dissuaded me from post flop play. One, in the middle stages of a tourney the average stack seems to be around 15 to 20 BB; this leaves very little room to manuveur post flop. Second, the hands these guys play absolutely baffles me, so i cant really assign them a hand range, and they are just waiting for an oppurtunity to call me down with middle pair or worse. Hence, i pretty much gain all my chips, in the middle stages especially, by punishing limpers and following up my pf raises with agression. My original question involved a hand i just lost in a 25 tounrney on empire. I have a slightly above average stack (~20 BB) and am in the big with aq off. habitual limper limps in MP, button calls, sb completes. all have me slightly covered except button. 4 BB are on the table. I push. Now i havent dont this yet in this tourney. button calls and turns over ak suited. this is not the first time i have had this happen to me. should i be using this tactic? if not what line would you take here? Also, any thoughts on postflop play in middle-late tourney appreciated.