Something similar happened to me with my 86 300E... It didn't turn out well. I was doing all the maitnence as told to do, changed the oil, sparkplugs, air filter and got the tranny fluid changed, I only changed the trani fluid because I didn't know how long it had been in there with the past owner and might as well change it to freshen it up a little. The tranny worked 100% fine mind you... I got the trani fluid changed and about a week later, it just totally gave up. Wouldn't shift.... I got stuck on the freeway during a sandstorm! out of all times, because I was driving nomrally and it would just shift into neuteral, the only way I could get it back into gear was flooring it and getting RPM's so high that it would somehow catch on and get me to at least 2nd gear. there were somedays where it worked like normal when it was cold, but when it warmed up all hell broke loose and it had a mind of its own, shifting in wrong gears and not shifting at all and then working fine like nothing ever happened. I didn't understand why this was happening, all I did was change the tranny fluid. Now on the other Mercedes forums it casued a big ol debate on how you shouldn't change your tranny fluid if its been in there awhile and others who said you need too. when I finally could afford taking her to the mechanic, it ended up needing a new tranny!!!
When he opened it up he said all the bands were broken and gears were messed up, but it worked 100% fine beforehand.... Still to this day with my 240D i'm hesitant to even touching that.... Or messing with it. I want to change it but i'm soooo afraid of going through all that again, and being a college student with no job at the moment I can not afford another 1,200$ tranny. Hopefully though you're not in the same situation.. I would advise checking the tranny fluid levels too, while it was being a skank (My 300E) I took her to a oil change shop and they said my tranny was a bit overfilled, so they drained some out and it worked just like it did before changing the fluid, but that was only shortlived and lasted about a week before going back to the crazy b**** mode lol
Good luck and keep us updated! sorry I wrote a novel
... Oh also I've been wanting to get a vavle adjustment too, does it really give you more power? I've heard it makes the car feel totally different driving wise...