Can you be more specific? Are you referring to the MAF volumetric efficiency and the ignition timing advance? Also, I plan on checking the OCV filter.MAF, timing, temps, etc.
Also, I've noticed that the drop in power occurs when I press down the throttle past 50%. Any less than that and it feels fine. Again, this only happens in the 2k-3k rpm range, so it can't be the tps.
Is there anything I can definitely rule out?
On another note about the orange stain on the spark plugs (from NGK's website):
Corona Stain: A removed spark plug sometimes has discolouration around the insulator surface which looks like gases have leaked between the insulator and the shell. This discolouration is generally called "Corona stain" and is caused by the fact that oil particles in the air around the insulator surface are attracted by the corona discharge, are charged, and then adhere to the insulators surface. The corona stain causes no deterioration of the function of the spark plug.