if you are getting a "rotten egg" odor only while under heavy acceleration it is most likely caused by a higher sulfur content in the fuel you are using. i experienced this problem while using crown brand gasoline in my crossfire. i haven't noticed the problem recently while using other fuels such as shell. here's a link to a tsb issued by toyota:

http://www.autosafety.org/Toyota%20S...l%20Models.pdf