Was this problem occuring prior to replacing the battery and alternator? Could it be a defective alternator? Something internal in the alternator draining the battery?

Assuming it's not the alternator but something else that's draining the battery then try this process of elimination. And the best part is this is not going to cost you a cent, unlike where dealers start yanking and replacing parts without any clue if the part really needs to be replaced.

Go to the fuse/relay box and pull every fuse or relay for any non critical electrical accessory or device that you can possibly do without such as cigarette lighter, wipers, defroster, dash lights, blower, fog lights, power windows, power locks, power seats, etc... you get the idea, and see if the problem goes away. (Take notes on what fuse/relay goes where, also take a picture with a digital camera if you have one) If the problem does go away, next gradually starting adding the fuses or relays back in, one by one and see which one makes the problem come back. Once you have the device/component isolated then begins the task of finding where in the wiring, circuitry to the device or if the device itself is the problem. This might be time consuming, but at least once the problem area is isolated it minimizes the guess work.