Hello, I have a year 2000 mercedes e240 2.6 v6 estate, which I think is a w210?The engine light came on so I had it put on a diagnosis machine and it said I had a missfire on cylinder 6. The mechanic reset it and the problem went, however it soon returned.I had it checked again and cylinder 6 was again missfiring, so I changed all 12 spark plugs and again it was fine until the car revs over 4200 the car missfires, but on diagnosis it shows cylinders 3, 4, and6 are missfiring. When reset the problem goes, but as soon as the engine hits 4200 revs the engine light comes on and the problem returns. The car performs and drives well under 4200 revs when reset. But returns as soon as it goes over 4200. Is this a coil pack?Ht leads? Dodgy spark plug or something more serious? Regards bert.