Hi - new poster but long time reader. Here is my issue with a relatively new to me w208 clk55 m113. Car has the following codes and CEL is on:
P0400 EGR
P0170 fuel trim
P0173 fuel trim
P0100 MAF circuit
and the following issue/s:

- rough/fluctuating idle, engine sometimes dies when coasting to a stop
- occasional misfire, CEL light blinks and car runs rough, no power, smells of unburned fuel
- also when putting tranny in park after a drive the rpms rise to 1200-1500

the misfire occurs maybe on 3 out of 10 drives, if I stop, turn engine off and immediately back on the misfire disappears and the car runs perfectly fine

the rough idle is also somewhat intermittent - it's never "glass smooth" like I find Mercedes V8s normally to be but it's reasonably stable when it's not acting up

the car has new plugs, wires and MAF including elbow seals, I replaced the upper breather hoses and cleaned the inside of the valve covers.
The vacuum lines that I can see look ok and since the issue disappears after an engine restart I am thinking my problem is electrical and not vacuum?

Any ideas where to look next ?

thx much All

2002 CLK 55 w208