2004 grand am question: for some reason my car has been dying lately. It did this a few times so the obvious thing was to buy a new battery- oct 2011. Everything was good for a couple months but I recently went on a trip for the weekend and when I came home the car was dead. I jumped it and everything was good until this week. I had a work conference and left wednesday at 8am. When I got home Friday at 5pm the car was dead again. I had an alternator test done before but could it be the alternator? There are 130k miles...