I think that the ITB's are usually not in harmony, making the car jogging loaded and generating the vibration sound. from A further forum wrote:It's possible I've missed this, but you've got a big tumble cleaner which can be substantial more than enough to suit engine heads? Re: ITB Conversion https://toyota-4age-blacktop-engi15825.blogoxo.com/26854511/new-step-by-step-map-for-jdm-toyota-4a-ge