FiTech EFI system

I've got accel decay, but in my logs there's no 'transient' value for when it goes super lean.

I've played with the accel pumps settings, and it only seems to make a difference with slightly larger tip-in values than where I'm experiencing the problem. When I max the gain and max the accel pump, just to see what if any effect it would have, my AFR's will drop into the high 9's, but then correct back to the target WOT AFR's within 2-3 seconds. So I know it's hitting the target WOT AFRs no problem, and only 'missing' them when I have accel settings too high or too low.

My cruise AFR has been tried at 12.9~14.9 - and the lean spike shows up in all of them to about the same extent. I've reduced the decay values and will continue to reduce them to see if it will lessen the issue - but as I mentioned, the log shows no transient fueling.

Another thing possibly worth trying is the learn speed value. I reduced it at idle to even it out and keep the AFR swings manageable, but the learn value seems to add 'momentum' to the fuel trim changes, and when my AFRs are headed lean, it takes until several revs after the spike goes away for the 'learn %' to swing the other way. I'll give it a shot over the next few days and see what I get.