I believe the ITB's are not in harmony, generating the car jogging loaded and creating the vibration sound. The five valve head is Toyota's reward into the 4AG after the 4AGZE went away. With the additional valve and independent throttle bodies- the 4AG twenty valve is a unique head style. https://toyota4ageblacktopenginef02233.tribunablog.com/how-much-you-need-to-expect-you-ll-pay-for-a-good-4age-engine-sale-40929385