My 280se 4.5 runs good, but when I drive at low speed (30-50) constant with not pedaling the gas pedal it has a engine shudder for 1 second. Also when I drive on the highway at 70 and push the pedal to the metal the engine exhilarate but I can fell a shudder in the engine for 1 second like then for another one and so one. The power of the engine is there but its is cut for one second then its there then again cut then there. The fuel filter is new, and the air filter as well as the spark plugs.

so what can that be??

cK

Check the injector signal from the injector points with a test light.