2002 Mustang GT, 49,000miles. The battery keeps going dead after about 5-6 days without driving. I can jump start it and drive for an hour and it will start fine as long as I drive it every few days. The battery is brand new (2nd one) and I have had the system checked out (Auto Zone) as far as the charging system. I have made sure everything is off, interior lights are not on, the shifter is in neutral, looked for a short but can't find a thing. I have to believe something is energized/shorted and draining the battery. How do I troubleshoot this anomaly and where do I start? Thanks.