I had a similar problem on my 97 E420. It was only giving random misfire codes and trim codes. The car ran like crap and had zero power. When I tried to accelerate, the check engine light would flash. Long story short, it turned out to be a blocked cat. The code reader wont tell you if there is a problem with the cat but there are some diagnostic tools that allow you to read the live data from the O2 sensors before and after the cat which will give you an indication of what is going on. Hope this helps, it was very frustrating and expensive for me when I had this problem.

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With best regards

Al