I was going to say that as well:
Change plugs and wires. IF problem persists try the coils.
If that doesn't work, get some injector cleaner (like STP or whatever) and dump it in the gas tank, run it through on 93 octane with that stuff and see if the problem STILL persists.
If that doesn't do it, replace the injectors.
Do all that and post back, I'm sure the stalling should go away. If it still does, and you said you've already changed the o2 sensor, then check the intake AREA see if anything is unplugged or accidentally knocked out (ACTUALLY, DO THAT FIRST, because your car will stall if the IAT or anything in the region is unplugged or loose).
Suneil
