Mis fire and Check Engine Light on 2005 Mercedes-Benz SL600

From time to time right after starting, the engine begins mis-firing and the check engine light comes on. I took to local Mercedes dealership and their equipment showed a mis fire on 1, 4, and 5. We replaced the plugs and a few days later the problem has returned. If I turn the vehicle off and immediately back on, the mis-fire goes away (Check engine stays on).

This vehicle is in excellent repair overall and I have done all the typical maintenances etc.

What could possibly cause this after replacing the plugs???????

Asked by for the 2005 Mercedes-Benz SL600
If the spark plug gap were incorrect or the plugs got "dropped" it is possible that the plugs are the problem. Check the electrical connections at the coils are tight and fully seated.
We changed the plugs and the exact problem still exist.
these cars use a central ignition coil for each cylinder bank, one left and one right. inside this "rail" are six
coils, but it is sold only as an assembly ($1250 each!!)
when you do you own repairs, no one, especially the dealer
will give you all the information that you really need.