What might be the cause of the engine overheating,
so far I have changed the water pump radiator cap cooling fan temperature sensor and relay, replaced the head and head gasket , correctly time the engine replaced the engine thermostat, cleaned and flushed the radiator.

 

Making sure all the air is out of your cooling system at this point should be top priority. Everything you have done is essentially everything you can do. If "burping" your system doesn't solve it, gas and a match will be your only solution

 

Have you also checked if your oil level is low?