Ok, everyonce in awhile, ussually when its sorta warm out and i take my car above about 4500-5000 rpms, i get a sulfuric rotten type smell coming from the engine. Driving my dads 03 Aviator a few weeks before i floored it to like 6000 and it had the same sorta smell. Does this mean that maybe the gas we've been getting in the area could have been bad? Or was that just a coincidence? Anyone know what it is?