Thank goodness for this post. This is exactly what my 2013 Lexus ES350 is doing and the dealership can not find the problem. I am going to take this tread when I take car in for 10K mile check. Like you I have tried different driving modes and different grades of gas. Problem is intermittent and sometimes more sever than others. Then I can go for days without a blip. It is very frustrating and irritating. If anyone has answers, please let us know.