Hello My name is Harry and I have been experiencing the same problems as you did...Lexus have put the car on diagnostics and had no errors codes showiing.They have cleaned the throttle body and is better but im still getting idling problems and stalling too.
Can you please email me some pictures on your fix you spoke about..It would be a great help to me...
My email add is: h4real@hotmail.com
Thanks in advance
Harry