Twingo diesel rough running

Sounds like a familiar problem. I had similar symptoms with my old Peugeot 308. Engine was stuttering and fuel consumption went through the roof. Turned out it was a dirty injector. Have you checked for error codes? That might point you in the right direction.

No, I haven't checked for error codes yet. Is it urgent? Can the dirt lead to engine damage?

It's always best to get it checked as soon as you can. While a bit of dirt itself may not immediately wreck the engine, the uneven fuel delivery caused by a clogged injector can lead to bigger problems down the line, like cylinder damage. I'd recommend visiting a workshop to have the injection system inspected.

Ok, thanks for the info. I took it to the workshop. Indeed it was the nozzle, it was dirty and also a little broken. 515€ later it runs great again.