Why does my temp guage keep going in the red

Did you bleed the system?

Did you check if the cooling fans are working correctly?

When engine is cold, check the coolant level. If it is low, top up the coolant. Without closing the radiator cap, start engine and allow to idle for 3 to 5 minutes. If coolant level drops, top it up. Close radiatro cap and run engine for another 5 minutes and allow to cool down before checking the coolant level again.

If coolant level is correct, check the cooling fans operations. Note if the upper hose is very much hotter than the lower hose, if yes, tyhe thermostat could be faulty. New components does not guarantee that it is good. Lastly, have a test performed to check if the head gaskets are bad if the radiator cap seems to have a high pressure when removing with cold engine.