Lean AFR @ WOT = mystery air leak

As the title suggests I am getting lean AFR's under throttle that suggest somehow there is a large amount of air that is getting in after the MAF, or the MAF is not working correctly. I did some logs and the MAF is only reading in the 150 range max. IIRC it should be a lot higher even for NA. the car is not registering any codes.



I have had my whole UIM off a few times over the last few months, first to diagnose and then swap the SSV solenoid and then to replace clutch master and slave cycinders. I am going to remove and reinstall the UIM this afternoon to make sure everything there is connected correctly and check the gaskets. Honestly the with the MAF reading being off by this much (40-50% if I remember correctly). I checked the Jet Air Bleed last night and it looks good in place. I will remove it and have a look if the UIM does not reveal a problem.



I have a few questions:



What should my MAF be reading (max range) under WOT?

Is there any other area to look for a leak (other than UIM and JAB)?

Would a failing MAF fit the bill for this and whouldn't that throw a code?

Same question for the primary O2 sensor?



Mods are listed in my sig. Anyone have an idea? Any help or suggestions would be great. Thanks for reading.