I am also having the exact same problem with my '98. I just bought it in June w/ 100K on the ticker. I experienced it the first week of ownership and was very *BLEEP*ed. I have not started to try and diagnose the problem because it won't do it when I want it to, only when I'm in a huge hurry running errands or picking up a hot date. I just wanted to add my "me too" to this post. This weekend I'll quiz my friend at the Lexus dealership and get back to you.