The pilot reported that his approach and landing were normal. After exiting the runway, while on a taxiway, the airplane “swerved to the right and seemed to accelerate.” Unable to control braking and steering, the airplane departed the taxiway to the right and proceeded through a steep depression before colliding with a wind sensor pole. The pilot secured the airplane and was met by first responders. The airplane’s right wing and fuselage were substantially damaged during the accident sequence. Postaccident examination of the airplane revealed that the brass splined bushing on the left engine throttle control shaft was stripped, which resulted in an uncontrollable, full power application to that engine. The wheel brakes were examined and no anomalies were found; the brakes held the airplane in place with the left engine at full power during a test run.