Ok...I'm on the same page now. Sorry.

You have the same volume of air passing through the entire intake as you did prior to the new housing (you haven't added forced air induction). The velocity of the air through the intake has decreased though. It has decreased proportionally to the cross sectional area increase, and the ECU thinks you have almost no air coming in.

Q = Flow rate of air
Vstock = Velocity of air seen by MAF
Vmod = Velocity of air seen by MAF
Astock = Cross sectional area stock @ sensor
Amod = Cross sectional area after mod @ sensor

Q=V*A
1) Q = Vstock * Astock = Qmod * Amod
2) Vmod = Q/Amod
1->2) Vmod = Vstock * Astock / Amod

Area of a circle = PI * R^2
If R is increased by 2, the Astock/Amod ratio = 4!!! Meaning that the velocity of air the MAF reads in one quarter that of what the ECU expects (this is a made up ratio, but you get the picture).

O2 sensors are designed to pick up a lean condition, but they must be warmed up to work (and the ECU knows this). Perhaps a simple reset of the ECU via battery disconnect is what is required, but I doubt it.

Perhaps we can trick the ECU into thinking that there is more air velocity coming through than it is measuring. Measure the resistance of the MAF @ idle under two conditions, stock and with the new housing. Then add some resistors in series (or in parallel depending on what you need to do) to correct for the idle problem (probably won't help when you're into the throttle though).

I think you're expecting way too much out of the ECU and will have a very difficult time getting it. Best of luck and let us know how the fuel management device works out.