ColaMike

I'm at my wit's end here. So, over the last year my '94 has developed an issue that I'm not sure is a battery, wiring, or starter issue. When it doesn't start, sometimes there's a low grinding sound, which I assume is the starter trying to turn. Then, nothing, sometimes a beep. My truck then sat for a while, then I sent it to AAA (they put on the new starter) to get it checked. They said the starter was fine, but the battery didn't hold a charge. So I had the truck towed back so I'd put in the battery myself and save the money. Then the tow truck driver started my truck and slid it into my parking lot no problem at all. It even started later. Maybe the terminals were loose and that drained the battery? I'm at a loss. Any advice?