Re: ITB Conversion on sixteen valve 4AGE On my stock bigport AW11 a leaking exhaust manifold gasket caused the O2 sensor to browse lean and it pumped gas in to the motor. Gasoline economy plummeted until I sorted it out. The engine's AFR seems usual at cruise, but rich at https://toyota4ageengineforsale72581.suomiblog.com/not-known-facts-about-4age-20v-for-sale-50264715