PLEASE HELP!!!!!!! Car still "broken"?

[1 bad chick]

I took my car to the dealership and they replaced the Idle Air Control Motor and cleaned the throttle body,but my car is still messing up. If I drive my car for longer than 30 min. at a time it will have problems starting and sometimes when slowing down at a stop sign/light it will just cut off. The engine will also shut off sometimes while driving, but will somehow cut back on without me having to do anything. If I just go straight to work (about 20 min. away) it doesn't give me any problems, but if i have to run errands after work before coming home, it will mess up because I have done some "extra" driving. Anyone have a problem like this? I was thinking maybe a sensor is going bad or my ignition module. Any ideas are appreciated, I'm taking it back to the dealership Monday, but until then I would like some ideas because it's driving me CRAZY!