Does your A/C blow out the defrost on to the windshield?

Shift modulation is controlled by a vacuum powered shift modulator. A
vacuum leak will make for hard shifts as the MORE vacuum provided the
SOFTER the shifts and zero vacuum = hard shifts. There's a vacuum valve
on the throttle linkage that reduces vacuum as the throttle is opened,
so "flooring it" will result in hard, snappy shifts vs. light throttle
applications should produce soft shifts.

Check the vacuum lines.

Leave it :-) It will last much much longer. Seriously. The smoother it
shifts the more wear it puts on the clutch packs.

But the reasons it's shifting badly now is you have developed a vacuum
leak to the modulator which controls the smoothness of the shifts. Very
common. As the plastuc tubing in the enfgine compartment gets old, the heat
and vibration eventually causes a leak and less vacuum means harsher shifts.

Get a vacuum tester "mighty vac" or soms such and test all the vacuum lines
carefully. Take one off, test it to see if it will hold a vaccum for a few
minutes. When you find the one that does not, put it back together, drive
to the dealer and buy a replcement. Some small and cheap part like that
is not worth buying mail order. If it's one of the rubber connectors you
can put a dab of silicone on it to seal the leak which should last a while
until the next one develops. It would be prident at some point to replace all
the rubber connectord and t's if you're keeping tthe car for any lenghth of time,
the same goes for the plastic tubing, although MB no longer makes the color
coded stuff any more it all comes in one color - black. Pity.

If you don't have a leak then eithe rthe fingers broke off the vacuum profiler
in that black box on top of the valve cover, again another cheap dealer item
of your vacuum mpodulator in the trans is brokeb which is extremely unlikely.

You have checked the trans for the correct fluid level right? And changed the
fluid and filter on a regular basis?

Erm, try Exlax?  ;-)

But, I would go with Karl's suggestion to check your vacuum lines for a
leak.