The sulphur smell from the exhaust, is actually caused by running the engine/cat convertor slightly lean for long periods and then running under a rich condition (ie going up a hill under heavy load) This is when the sulphur smell (rotten egg) is produced.
Under relatively lean conditions, the sulphur found in gasoline is converted to sulphur trioxide, then during the rich running condition the sulfur trioxide is converted into hydrogen sulphide (rotten egg smell) within the catalytic converter.
The root cause could be an O2, vacuum leak, secondaries, fuel pressure, MAF, EGR...
Try to get that code pulled.
Also, some gas will have more sulfur than others. This will not affect power but it will affect the smell and the longevity of the catalytic converters.
