How to play qualifiers/steps on the bubble with a big stack?
 

im having problems closing the deal when playing in qualifiers/steps.

I am frequently getting myself in good positions and then blowing it, for example,

2 qualify, down to 3 left

Hero has 7500, player A has 5000, player B has 2500

or

Hero has 4500, player A has 8500, player B has 2000

blinds are around 75/150 to 100/200 at these points.

How would everyone play these?

Continue stealing blinds?
Tighten up considerably?
Try to avoid the other big stack?
Get aggressive on the short stack?

Any comments appreciated as this is happening a lot at the moment and is seriously damaging my roi.