FYI, The transmission has to heat up to 153 degrees to reach optimal shifting, And is quite normal when cold [ less than 40 degrees ] double check the fluid level, I would install a inline trans fluid filter. The fluid should be red when you check it not brown, Use a white paper towel to determine color. If you get a flush bring it to a toyota dealer[ cheaper labor/fluid than LEXUS stealer ] Good luck and keep us posted.