The main realy has been know to cause a problem like that with the stalling . If you call teh dealer and ask for a main realy they should know what you are talking about
I'd also suggest having the dealership check the OBD/ECU, too. Mine went bad and caused strange electrical problems (in my case, it set off the alarm whenever the hell it felt like it.)
You can check the ECU codes yourself with a jumper - DIY (Do it yourself) instructions are available on this site. Sometimes in if the OBD craps out, it wont give a reading using this trick and the dealer will have to check it. That's what happened to me, too.