I have a 2005 F150 with the 5.4L V8. There is a bad smell like rotting eggs and my friend said there was a sulphur smell as I dropped him off at his house, he said my catalytic converter might be bad. I looked it up online and I found mainly change gas or bad converter but I also found a thing that said lots of Fords have this smell when its cold. It has been abnormally cold this past week, and I have been driving my truck short distances so it never gets time to warm up. Also, the last time I filled the tank up it was with Murphy USA gas which I know isn't exactly good gas, but it is cheap. Could either of these two problems be it? I really don't want it to be the converter and I don't think the problem has gone on that long, my friend commented about it yesterday and today and I take him home a few times a week so it probably would of been noticed if it had been a longtime issue. Thanks.