Interstar rough running

Sounds like injectors. When they get clogged, they don't spray fuel properly. Is it smokier than usual? You could try an injector cleaner, but honestly, if it's that bad...

Smokier, yeah, a bit. Injector cleaner, right, I've seen those. So, you reckon it's just a case of gunk in there, and not, like, a major engine disaster?

Could be just gunk, but could also be a valve gone bad in the injector itself. If cleaner doesn't sort it after a tankful, get it looked at. A garage can test them properly. Could save you money in the long run compared to running it poorly.

Cheers for the advice! Garage diagnosed a faulty injection nozzle, said it was dirty. Cost me 515€ for a new one. Runs like new now!