Why don't you see if your problem isn't a problem.
With the engine warm, and at a stop, put the shifter into 2 and then back to D, this will engage a first gear start. And then accelerate, and see if it's not "sluggish" anymore because of first gear. Or you can simply floor it, engaging kick-down, which will get you into first gear.
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!)