Lots and lots (and lots) of debate on this subject. Let me correct you right away: per MB, the transmission requires NO service (fluid change) and that's my recommendation too; leave it alone. MB does NOT recommend changing it at 100,000 miles, if the dealer told you that, they LIE.
There are alot of posts on the subject. Here is one where I quote a handout given out at an MB training class, it's the 9th post down on this thread:
1999 S500 with 722.6 Automatic Transmission Filled for life?
I'll let it go at that for now. I understand other people have their right to their own thoughts on this, that's fine.
As to your problems on your truck, they could look at possibly the Mass Airflow Sensor, also transmission adaptation could be checked, and they could properly check the fluid level (see the 9th post I mentioned in that thread).
Gilly