Can you see how far down the "heat" goes into the threads ??, what color is the soot on the insulators ??, is it gray or tan or black ??, is there any silver specs ??, How far is the discoloration down the insulator ??, what heat range of plugs are you running ?? from those photos, they look like "extended tips", that can alter the appearance some on the insulator too... Does the car lay down or surge at speeds ??, hard to tell from a photo, it might be ok, if you don't see heat going down the threads about half way down or you don't have any surging or flat spots it's probably not too lean... Like Hemi-itis said to get a really good plug reading, idling around or cruising, your still on the idle curcuits allot, gives you a false reading, you need to shut the engine off after a "hard full throttle run", don't re-fire it, pull the plugs or at least a few, especially the rear plugs, right afterwards, to get a proper reading... here's a couple descriptions & photos, some are hard to read {4th photo down, or the one with the blue boxes around the descriptions, is a really good one}... Hope it may help explain what I'm asking & what to look for some... Good luck
The insulator is pretty light and the ground tab is super clean,but the base of the plug at the bottom of the threads is black.
