I changed my plugs yesterday, 44K on them, I have a 2K1 Auto. Plugs were black with deposits. From what I found that indicates a rich mixture? Is there any way to correct? The ECM should take care of that correct? Can the throttle cable affect this? By the by, cylinder #3 had little black spikes on the outer edge. I worry all the carbon buildup is causing some detonation- fixed by the ecm, but then retarding and resulting in loss of power. Also use 91 or 93 octane.