1997 Dodge Caravan ALTERNATOR

i have 97 dodge carvan , and my battery light came on so i check to see if my alternator was working so i took one cable off the battery to see if it will stay running so when i did this it cut off i took off the alternator off to get it check out at auto zone and it check out good i put it back on charge the battery back up, put the alternator back on drove the van for a little while and it cut off again so then i change the belt, put everything back together charge the battery back up,test the battery and it good. drove it around again and it cut off again while i was driving so what else come be wrong because i have had the alternator check twice once at auto zone and once at krangen and both time it was good so were do i go from here.