92 Grand Marquis....battery goes dead, suddenly
 

I have a 92 Merc. G.M. and recently, the battery goes dead, all of the sudden. It usually happens at the worst possible time or at the worst possible location, too. I have a 16 year old daughter who seems to have bad Ju-Ju when driving this car, and it is the only way for her to get around, most times.
I have had the battery (AutoZone Duralast Gold) tested twice at full charge and it comes back good. I have also had the system scanned when running and all comes back good. The system test is mainly for the alternator, in my thoughts, but all is good.
I replaced the positive battery cable, after the first episode, but it only took five days for it to happen, again.
ANYONE have ANY ideas for me to try?
Lost in AZ,
LaMont
email: lamont@mannkrafted.com