First the system: Mopar LA 360, Stock 4BBL cam (430/444 268/276). Torker II single plane manifold, EZ-EFI 1.0 with color dash 003 tune, MSD streetfire ignition, stock dizzy. Engine makes about 18 inches of vac at idle. Idle 13.3, Cruise 14.3, WOT 12.7 I've noticed that when I go WOT, the AFR Target (not actual) isn't always reading 12.7 AFR. Sometimes it reads that, sometimes it reads leaner. The leanest it's read is 13.1. I called tech support and they hadn't heard of it but the word came down from a higher level that this is normal and the target could move up to 0.5 AFR. Now all that is fine. It runs great and if 13.1 is too lean I can always drop another couple points into it. My question is why? There must be some reason the ECU does this, I just can't dream up a reason.