1997 Toyota 4Runner No heat but overheating?

I’v basically had no heat all winter from the main heater or the rear. I have back flushed the heater core and the engine was rebuilt 2 years ago with a new water pump. Recently the truck started overheating in the morning. If I stop and shutdown for 10 min it runs normal the rest of the day.
Oil looks fine, trans fluid is clean. Any thoughts….