I have a misfire in my 15,000 mile 2010 California only at heavy throttle at 4200 rpm on up. The dealer (they seem sharp) says its an injector OR two that are clogged on one bank. BUT its a HARD misfire I am struggling to believe it and they don;t seem confident enough to sell it to me as "the fix" to my problem. Its a hard mis, like an ignition miss. The system reads lean when its happening (ignition misfires can also show a lean reading) and fuel pressure is rock solid. I am unfamiliar with Direct injection, but typically misfires from being lean wouldnt be so aggressive of a hit on the misfire (this feels like AND sounds like a rev limiter/ignition interrupter...but it allows the engine rpms to climb). Also it happens at EXACTLY 4200 rpm on up everytime when you are beyond 4200 rpm. If you run the engine below half throttle it will run real high on rpms without a miss. Only under heavy throttle do you get the violent miss. Ideas anyone? Thanks in advance.