I suggest you change your fluids before you do anything else... Simply drain the fluid from the pan drain bolt... and refill... then drive for 50 miles... and then repeat the procedure again.
The third and last one... drop the pan and change the filter. I also suggest you use Valvoline Dextron ATF... I have great experience with this fluid on MB... very smooth action. You can also try a Valvoline Maxlife with sealer (1 quart only) for your last fluiid change... they claim to "replenish" the seal so it doesn't leak... to fix your flaring... If it doesn't fix your flaring, then no harm done... you know when it gets worse, you will have to do a tranny rebuild.
I think your valve body is sticky or leaking that the tranny act funky... possibly due to that the tranny fluid may be dirty or has not been changed for a long time.
My car once started to act very bad... rough shifting... because I didn't change the fluid for 4 years... and after I did the flush, it was kitten purring.