Well...
The results are in!!

My ACCELERATION RESISTANCE was a symptom of a worn Front Flex Disc. Part costed me about $60 (from here)... and I don't know what the labor costed, probably about $200. I'll find out later. Thanks for everyone's input and I'm so glad to have this problem solved! This post ALSO helped me to figure out that I had worn lower control arm bushings also. You all made me lose $700!!

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2006 E350 w/ 155k miles (Daily Driver)

Previous:
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!)