Just took her in...
 

Just dropped my 08 E350 4Matic off at the dealer this morning. Had been having hard shifts since I got the car in 2012 and thought it was just a characteristic of the transmission but the yesterday when I went to take off from a red light it revved to about 4K and started crawling. I pulled to the side of the road and restarted and it was fine. I didn't get any lights or anything. The car was in comfort and in standard drive. I did the transmission service at 41K and 83K and its just about to turn 86K thank god my warranty still has about 300 miles left on it. Never had any major issues or break downs with this car so I'm hoping its nothing.

Oh its something. Hope won't be enough haha. Probably a conductor plate, or your fluid level could be low, or a valve body.

Dealer called, they have had 3 techs look at it and hooked it up and there are no codes on the car, all fluids are good and clutch plates and the valve body appear fine according to the computer. not sure what else is next. I am wondering if maybe a filter gasket could be leaking a little air causing the transmission to slip.

Do you have 5 speed, or 7 speed?
Typical for 5 speed is wet plug due to aging orings on pilot bushing.
I would not be surprised if 7sp had the same issue.
I am still learning the software, but from what I heard if the car goes into soft limp, it HAS TO have pending code in memory as those codes will never erase themselves.
How-come 3 dealer technicians could not find any.

Could still be the valve body or conductor plate. If the symptoms are not severe enough, codes will not show up on the computer. The techs will not spend the hours of time to reach and diagnose these parts(even if they really are faulty), not unless you pay them way more than the simple diagnostic fee. Good luck though, keep us posted.

Had similar issue, had it checked by dealer and no codes were found. 2 days later transmission completely failed on the highway. Transmission and Valve body had to be replaced. Took a month getting it back since I was dealing with warranty...

So there could still be a issue with yours, just stay alert!

I still have hard time to buy the story about no codes.
Had my 2004 model scanned by friendly technician and the car had over 30 stored codes.
Only the one for seat height sensor was active. All other happen probably before I bought the car.
Bottom line, the car remembers even that you had burned bulb 5 years ago

There is a pressure test they could do but that requires you to pay diag time. If its that bad see if you could find a used trans. And believe it or not if you have average mechanical skills you could replace it yourself.

I've had a mild case of harsh shifting for about 2 years now. I've brought it into the dealership several times, had a tech ride along and agree that there was an issue, but when hooked up to the computer, no codes. We've looked at the shift adaptations several times and they just weren't severe enough to throw a code. I mean if my transmission just failed on the freeway then yes, I'll get a code. It's not always as simple as yes code = error, no code = no worries

It is the 5 Speed, so far no issues, I went ahead and disconnected the battery overnight and reconnected it and it seems to shift better in my opinion tough to say way the future holds.My daily (MK6 TDI) shifts as smooth as butter and my Manuals have never let me down.... slushboxes on the other hand are another story.

I hope you are aware that you are dealing with adaptive transmission.
It will adapt to your driving style.
Disconnecting the battery reset the computer, but unless you change your driving habit, it will come to the same behavior.

Yes I am aware of the whole adaption process and all. My mother is the main driver of this car and she drives it like an absolute grandma... Honestly I think when she drives it, it never goes over 2.5K. So far we have put about 200 miles on it since being at the dealer and reset and had not had any harsh shifting or slippage.

Having warranty expiring shortly is not giving you much room to play, but saying you had transmission serviced in the past, what exactly was done?
Full flush with pilot bushing replacement, or 2.5l drain from the pan?
Per my experience replacing pilot bushing is crucial on those transmissions.

We did the full flush with the pilot bushing replacement.

Was the plug dry or wet? Did you check for ATF in computer module?