I have a 2004 W211 E320 and few weeks ago my engine started misfiring. I changed my spark plugs i know its not ignition coils they've been replaced too. My only guess is the cats. Missfire occurs when i go 3500rpms and up the engine starts making weird noises and eventually shuts off after like 2 mins. I changed my primary O2 sensors too. Any help would be appreciated. The car starts shaking too and the engine won't accept any throttle.