Hi, I have a C270cdi 2002 saloon model. recently when I boot down she's been chucking out a nice plume of black smoke before taking off as usual. Not that surprising for a diesel engine that's done 116k miles. However now she often doesn't take off or boot out any smoke, just builds up speed gradually and even with my foot to the floor only gets up to about 90 mph. Any ideas? is it my turbo? and how can I check this? Thanks for any help or advice anyone can offer. I must admit last service I failed to replace the fuel filter due to the parts supplier giving me the wrong unit. I am planning to do this at the weekend, just in case its a fuel thing.