I have a ford explorer and the driver side door
won't stay closed. I checked the latch and it is not
stuck in the closed position. It moves freely, and
will not stay latched. Do I need to replace the
The door latch should be stiff, hard to click down, and with the door handle pulled, hard to reset into the open position. Yes you would have to replace the latch.
The latch should not move freely up and down. It is not hard to replace although tiny hands are a benefit. Best download a schematic of the latch and it's removal. Some operations of removal and reattachment may have to be done blind on certain models.
My driver side door want stay close