You mentioned a "kick" when downshifting in your 97 c280. This is equipped with the 722.6 tranny and if the car is still covered under factory warrenty I'd schedule a appointment, complain about the 2-1 downshift and tell them to fix it. :-)
The .6 is a damn good tranny but, the early ones have some issues with clutch pack clearances, input shaft bushings, front and rear "freewheel units" (spags to the rest of us) and some very early production ones have no covers on the solinoids which can allow normal debris to collect on the contacts and short them out.
The "kick" is normally the byproduct of 2 things, early freewheel units that will "miss" when locking up and ECT programming. There are a bunch of DTB's on these and depending on the wear of the bushings replacement is oftem the cheapest route out and always replace that ETC.6 control unit as they have to match the valve body for proper performance.
This is also a good time to bring up another point, this unit has no dipstick and uses synthetic fluid that is kinda hard on the skin. The only other weird thing I've seen with the .6 is the electrical connector will leak internally and "wick" atf into the harness all the way to the control unit. Regardless of the recomended spec's I'd service this unit every 60k and be prepared for a shock when it comes to fluid costs.
BTW, I've seen a few sets of collasped motor mounts on 202's and 210's at a early age.
Project Smoker, '87 603 powered wagon
Hauler, 96 CTD can you say torque?
Toy 73 Cougar xr7 convertible
Acme Automotive Inc.