1998 contour overheating

Replaced the waterpump, replaced the thermostat. Will still overheat. Water will run out the overflow tank. After filling it up its usually will not overheat for a day or so. I removed the thermostat and let it run without one thinking maybe water was being constricted by something behind it. No difference.

Help please.

Have you checked to make sure your cooling fans are coming on? It's simple, but often overlooked. Good luck with it.