The article in the link below is for the W203 supercharged engine, however the symptoms very closely to what you describe. I just thought you may wan tot take a look at the article.

Site link:
https://www.mbwholesaleparts.com/StarTuned/html/index.html

Article Title & link: Engine Performance Complaint from "False Air" Model 203.040/740

https://www.mbwholesaleparts.com/StarTuned/pdfs/Mar08_ServiceBulletin.pdf