2004 Ford Expedition.

engine dies when driving slow. battery light comes on when at idel, took
truck to auto zone to test it out and they could not get a read from it, they said they had a simalar prblem with another customer, and that person said they went online and they figured out it was a fuse blown somewhere but they couldn not tell me where, does anyone have any idea where i could look, so i can get my truck diagosed, by auto zone?