I have a 2005 Chevy trailblazer LS the water pump is changed the coolest is a good color the thermostat is good and it's not vapor locked and it still dramatically overheats what's wrong with my vehic

Make sure all the air is out of the cooling system, fans are working, serpentine belt is tight. Squeeze hoses when engine is running and feel for proper pressure. Check hose to overflow bottle, any cracks can prevent it from sucking in coolant as needed. Check radiator cap as well, those usually need to be replaced every few years as well. Back to the fans, if they aren't coming on when they're supposed to, check fan controller, ECM, or engine coolant temp sensor. If still no luck, dig deeper, check radiator for flow, test coolant with "Block Tester" for a blown head gasket that may be causing overheating.

Check the fan relay, does your truck have a clutch fan? Even if you do have a clutch fan there is a fan relay replace it see if your problem is fixed.it fixed my overheating problem