I have replaced water pump, thermostat, and have had the radiator flushed. The truck is still overheating. If anyone can help, please let me know.

Flushing the radiator will only clear the tubes that already are flowing coolant.
Depending on your mileage, you may need to replace the radiator and perhaps the hoses as well. That would save you time and money later.
You may want to check the cooling fan for proper operation.
You need to have proper fan operation even with a good radiator.

This link should help:

https://www.askmehelpdesk.com/cars-t...tml#post235973