2002 Ford Focus car dies

my wife drove the car about 4 blocks and gages went dead and car dies ,won't hardly turn over, jump car and it starts.drove home and cleaned battery cables and charged battery. didn't check battery to see if it need it though.next day drove to work 15 miles in dark lights on no problem drove home in afternoon with ac. on, no problem. wife goes across town 10 miles no problem till coming home it dies getting on interstate. waits 5 min. it starts slowly so she drives with lights on another 4miles then the gages go dead idiot lights come on and dies, won't start i go jump it then it goes the rest of the 5 miles fine idle in driveway with lights on,turnrd off it started agian