I have same problem. I took the car to Lexus dealer and they say AF sensors are not communicating with the ECU. Recommended replacing the brand new Denso sensors and if that doesn't work replace Co2 sensor which I did. I also put in a new OEM MAF. Nothing has helped! I am thinking about replacing the sensor on the throttle body to see if that helps. My mechanic said he could not find any vacuum leaks. He did say there was a very small leak in the throttle body but didn't think that would cause my problem. Any help or ideas will be appreciated.