We have a 5.3L, 12587603OS we are trying to find where our commanded timing is getting skewed. Seems to be pulling 3 degrees above 4000rpm but only at WOT or close to. We have been through all the standard tables, IAT, ECT, Ethanol,Torque management, Fuel Mixture Corr. ETC. We went to a COS to see if that would help, still the same. Any help would be appreciated. See calibration below, Thanks
COS3.ctz
EST LOG.efi