I have a lexus es300 and it runs fine till it gets a little warm. Then the cel will come on and when you push the gas it will die. Also when this happens the scanner will not communicate. When it is running fine cold the scanner does just fine. Just soon as the light pops on and you can hear hickup if you will, thats when the scanner says loss of communication. I have even run it without the converter on it and same results. Thanks for any help.