1993 W140 with recent increase in sulfur smell

[rschach]

I have noticed the heavier sulfur smell at stops and after driving. I know this is typical output from the catalytic converter however the recent increase concerns me of pending problems or something clogged. Is there any "at home" or DIY options here such as gas additive,etc....to relieve any potential sticking valve/clog, etc. prior to taking to the shop?

[rschach]

Just bumping this back up hoping to get some help on this situation with this 400SEL catalytic converter.

[lyonstexas]

To address your concerns of possible clogging, I have in the past used two sheetmetal screws and a drill bit to test for clogging. Drill a hole before and after the suspected device (muffler, cat, pre-cat) and start car . Check for pressure differences before the device and after. if virtually no difference, then your in good shape. If a very noticeable difference is present, you probably have a clogged device. When finished, screw in the sheetmetal screws to seal, and the next time you are at a muffler shop have them remove the screws and weld the holes shut. Better sooner than later to avoid carbon monoxide leaking into passenger compartment.

Tim