engine is hunting

Question by omarelmokhtar posted 6 months 2 weeks ago in S-Class

hello every one i have mercedes W221 S500 model 2008 and there are misfiring in lift side in the four cylinders and i replaced all spark plugs and all ignition coils and disassembly the all engine to check the pistons and the valves ... etc and still there is misfire and i replaced air mass and the injectors and still there is misfire and replaced 3 engine control unit and still there is misfire in the same side and i replaced the o2 sensors and still there is miss fire in the same side

there is any one can help me