I would put it into first gear, and then just try and get it up past 3,000 slowly... but then again, if it runs really rough, I wouldn't want to hurt it.
I agree with Jim on trying to get the cheaper fixes first... maybe you could try some of the X66 stuff (recent discussions on it) and see what happens if you still believe it's carbon build up... but carbon build up should slowly burn away the more you get the revs up... seems weird. Try a bottle of Techron also... what gas are you using? Good luck.
2006 E350 w/ 155k miles (Daily Driver)
1993 300E 3.2L Sedan w/ close to about 300k miles
2003 E500 Brilliant Silver (Had 217k miles when totalled!)
1989 300E with 289,000 miles (had for <1 yr while in HI)
03 CLK 500 cabrio (Mom's)
2006 C230k (Dad's)
1999 S420 (Mom's/Dad's)
2000 C230k Sport sedans
2001 CLK320 Cabrio (Mom's)
1995 C280 My First Mercedes-Benz... (155k miles. EXCEPTIONAL AUTOMOBILE. Was Very hard to let go of!)