Diagnosis & Repair

WARNING: This page is about a different car, the 2003 Lexus GS 300. However, it is still accessible from the selected car via links, so may be relevant.

Check throttle control motor. See THROTTLE CONTROL MOTOR (GS300 & IS300) in SYSTEM & COMPONENT TESTING - GS300, GS430, IS300 & LS430 article. Replace as necessary. If okay, go to next step.
Remove the intake air resonator. Check whether or not a foreign body exists between throttle valve and housing. See Fig 1. Remove foreign material as necessary. If okay, replace throttle body.

Fig 1: Checking Throttle Valve
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