AFR goes down 3 points after a few days.

I am trying to figure out on why my setup is running 11.8afr at wot once I reset my trims. After a few days it will then settle to 11.5afr at wot and the ltft corresponds with adding 3% fuel to make that 11.5. I can feel the difference. I understand weather can have an effect but it is not. I.E morning is usually richer and after work it is leaner. This is not the case and I wish it was. I am running boostane and 93 all the time. I have changed the target afr from 11.3 to 11.5 in the tune with no change at all. I could try removing that 3% from the maf but, I will be in the 12s and not feel safe. Then after a few days be at my 11.8. I don't think this is realistic.