Take it back to the dealer and reference the following TSB's
1. BR003-02 (rear brake vibration)
4/4/2005 - 2000, 2001, 2002, 2003, 2004, 2005 Toyota Tundra. New brake drums have been introduced for use as service parts on 2000 – 2005 model year Tundra trucks to reduce rear brake vibration. The new drum has increased mass and rigidity.
2. BR004-02 (front brake vibration)
4/4/2005 - 2000, 2001, 2002, 2003, 2004, 2005 Toyota Tundra. Under certain usage conditions, some Tundra trucks may exhibit front brake vibration. Improvements have been made to various brake components to help improve this condition.
or and additional TSB...
3. BR005-06 Inconsistent or unusual brakge feeling
3/17/2006 - 2003 – 2005 model year Tundra vehicles produced BEFORE the Production Change Effective VINs in this TSB.
Some customers may experience a slightly lower brake pedal feel intermittently. A new brake pad anti-squeal shim service part has been developed to address this concern.