Ah, yes, the famed Italian tune up. There was recently a thread about whether this term is an affectionate reference to a time-honored tradition, or an insult. I hope it's the former.
In any event, many, many died in the wool MB fans have told me that these engines really benefit from some occasional flogging. The idea is to find a safe, hilly area and once a week or so give your engine a couple of wide open throttle (WOT) experiences for several seconds. You'll see the tach go to redline (6000 RPM) and you'll almost lose your nerve, but be strong and persevere, and good things will come. If you have carbon buildup, the first couple times you do this you'll think you've ruined your engine since it will buck and snort when it hits about 5500 RPM. But, again, be strong, keep it up, and before you know it, she'll be purring like a kitten. This did happen to me, but fortunately Stu Ritter had said what I just said about not getting shook up about the bucking and snorting ...
Some have even reported transient electrical glitches seem to improve after an ITU!