Recently got a call from Lexus HQ customer service where they, for first time, acknowledged they had a problem and said engineering had been directed to investigate for a possible fix. Whether this really leads to a retofit solution remains to be seen, but at least our complaints are getting through and they aren't simply stonewalling. Keep up the pressure and be sure to give really negative feedback when they call for one of their customer satisfaction surveys.
Have tried using BP gas and here (in Michigan) it didn't help. I believe there are regional differences in gasoline, however, so perhaps it helps elsewhere and perhaps BP will market the low - sulfer gas here later.