2005 chevy equinox overheating

So im working on this equinox and it has a new
thermostat, radiator, and water pump. The fans do
turn on. I drove it around and it was fine but then i
went to the store. When i parked it was fine but
then i came back out and there was fluid on the
ground, i assume from the overflow, and it was
overheated. I drove it again and it cooled down and
then in the drive through line it overheated again.
Whats going on?