When I back out of the driveway up a slight grade the car surges, actually pulses as if i would if i pressed the throttle on and off. It's not the engine because the revs aren't changing...so I'm guessing it's the transmission or the fuel supply? Anyone have experience with this? Thanks.

Does it feel like the transmission isn't catching the reverse gear?
I have this problem too... sometimes when I push the gas, it feels as though it's barely in reverse (if that makes any sense), and then when I push on the gas (some more), it will catch and jolt the car. Does it feel like your problem is trans related?

I got an answer to this a little while back. Don't recall what it was though... I'm sorry,,,, Do a search! You'll find the info. Also, it doesn't seem to be any sort of major problem.

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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!)

No the car is definitely in gear. It just feels like as if i were throttling and then getting off the gas quickly every half second. Again, that's the effect, but the engine isn't actually throttling and again only in reverse. Any ideas? I'll try and do a search also.