2003 Ford Taurus extremely frustrated

This is my third taurus and I purchased it with 10000 miles. I have had problems with this car since I bought it. It all started with dead batteries so I replaced it and still had the same issue so the altenator was replaced 3 times. Still dead batteries so the dealer checked and replaced all the ground cables this didn't fix the problem so then the Gem module was replaced, it still killed the battery so I put another battery in and the problem went away for 2 years but now it is back. The battery had a short internally so it was replaced which seemed to work but then a week later it started again. The charging system was checked and the battery was tested good the alternator puts out 14.5 volts except first thing in the morning with the lights on it charges between 8 and 11 volts. We then checked for a short with the test light method, with the ground off the battery and a test light between. The light rapidly blinked bright and off constantly. It has been suggested that the Gem module is bad again but before I shell out another $900 is there a way to test the module to make sure it is faulty. FYI my cruise control, wipers and lights all are doing strange things but not all at the same time.