2002 Chevy Blazer 02 Chevy blzr.--Won't stay running

Have had problems starting for months. Battery would charge and drive for days. First time I let it sit for more than a day without driving it I'd have to charge the battery again. I just charged battery at autozone and it tested good. Went home and it started right up. Drove about 4 blocks then died and now won't start again. Tries for a few seconds and then just stops trying