2013 Mercedes Sprinter EGR valve cleaning procedure, do every 15,000-20,000 mi, stops coughing

Mercedes factory repair procedure replaces clogged and sticky EGR valves when they get gunked up with carbon. I have been cleaning mine every 15k mi or so since it started bucking and coughing around 32k mi. And it has been a reliable preventive maintenance. Around 90k mi the servo motor went bad and I replaced the whole unit. But by 90k miles most people are on their third or fourth valve! It’s super easy to clean. Here’s how.