[davesdeville]

The rotten egg smell may be indicative of a cat that's already going bad. It might go away after the catalyst beads are gone.

My friend had some exhaust tubing and a perfectly good chrome tip so we cut off the resonator and replaced it with that. It didn't change the sound at all but I never took it on the freeway to see if it increased the drone.

Take a look at the cap and rotor and if any contacts don't look good replace. The plugs should be OK, I mean it won't hurt to change them but it won't do much good. At least visually inspect the wires for cracks, and take a look at them in the dark with it running, if you see any electricity 'leaking' from them it's time for some new wires.