2003 Ford 350 Van 5.4l

The Battery and Alternator test good. The last time driving the vehicle, the
ABS and Battery lights in the dash came on and the battery completely went
dead. Before this time, the two lights would come on and off intermittently
while driving and also loose power a little bit. This seems to happen after
driving awhile. Any ideas, we are thinking it could be the alternator.

Keith