Lots of eggy smells used to come from catalysts pre ultra low sulphur petrol. Now it's quite rare. If you don't fancy paying a garage to check the cat, try an Italian tune up. Really hammer the car, right up close to red line. The extra exhaust heat will help burn off any contaminants in the cat. Maybe throw a good dose of redex in there too? A good hammering once in a while does an engine some real good. Helps to get things moving, maybe also try to disconnect the battery over night afterwards to reset all ecu parameters for relearning. That often helps the car feel perkier. I'm coming from Alfa Romeo and Fiat ownership where this is a monthly need in some cases!
2005 Focus C-Max 1.8 Petrol Ghia + Sony 6 disc, 2007 tail lights, Led bulbs all over and HID front fogs.