Hello and welcome to JustAnswer!
Did you replace the parts that have already been replaced or was it a shop?
The truck had to have the engine replaced. So therefore all the parts are new that needed to be replaced, but no part was replaced that was attached to the block. The engine that was used to replace the engine I had was running before the engine swap. So yes, I have been the one who has replaced all of the parts, not a shop.
Ok. If you've had the cooling system open to replace parts and didn't bleed it then that could be your problem. Any time a cooling system is open it has to be bled or trapped air will cause overheating.
With the engine cool remove the radiator cap, top off the coolant until it's near full. Start the engine and allow it to come to operating temperature. As it runs you may see air come to the top. As it nears the point where the thermostat will open you will see the coolant rising and becoming unstable, eventually you'll see the thermostat open. The coolant level will drop and you'll see flow.
Top it back off at this point and make sure no more air is coming out. If you don't have heat then raise the RPM's to force air out of the heater core. When the engine is at full operating temperature and no more air is coming out of the cap then you can top the system off, install the cap, and top off the coolant reservoir if necessary.
This is best done with a special funnel that is attached to the radiator cap opening but can be done without it. Just be careful of the hot coolant and steam while the engine is running.