Contour Enthusiasts Group Archives Forums General Troubleshooting what cuases that sulfur smell @ 3K + rpm

Every time i rev my car passing minivans, or luaghing at civics, i get a very harsh sulfur smell, car runs perfect, although i do only get 250 miles to the tank. I did a search and most people have said its due to a bad cat, i just want to make sure that it can't be anything more serious, and find out if its covered under ford's warranty. my car has 43,000 miles on it (check sig), and if so, can i take it to any ford dealership, even though i bought from a joe shmoe used car dealer?