I have found that my 54 plate CLK 240 auto will drive over 3000 revs through the range at normal speeds, but when driving on the motorway at 70 mph plus and hitting 3000revs the eml light comes on and the car drives like a 'bag of spanners' if I stop the engine and then restart the car again the car drives ok but the eml stays on, garage diagnostics says 6 cylinders misfire!!! please help