Sounds like the headgaskets are out of it. You didn't do anything wrong.
The 3VZ (3.0L) was known for this.
See attachment and call the TOYOTA 800 number. 1-800-331-4331 and tell them what you think is wrong and see if it is still covered under warranty. If they ask, tell them you did a search on the internet.
They should be able to tell you with the information you provide them.
Good Luck
__________________
2002 TUNDRA AC 2WD = NOT STOCK
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