With my 500E, at 2/3 to 3/4 throttle the car's power surges slightly, whereas at WOT (wide-open throttle) it pulls as smoothly and aggressively as one could hope. And the car's not down on power; G-tech proves it. And there's not a speck of carbon in the combustion chambers, as that's been delt with (BG44k right into the intake manifold-sucked it in thru the brake booster vacuum line, shut the car down & let it rest for an hour, then watch for a cloud upon restart).
The surge does not appear especially noticeable at the point where the variable valve timing kicks in; I'm quite familiar with that sensation
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Any thoughts are appreciated.