As I suggested above, file a complaint with NHTSA. If enough people do that, Lexus will be forced to fix the problem.
There's always the 'sue them' route, but I don't like getting lawyers involved unless absolutely necessary. You may feel differently.
I also have the same problem with my 2003 ES300. Has anyone tried the Lemon Law? I'm a Lexus fan, but this is hard to deal with. My life passes before me at least once a day as I push my foot down on a unresponsive pedal!!!!