Thanks for the replies. I was able to sort out my lean condition and now have AFM's beween 11.3 and 12.0 under WOT.
On the stalling issue, I agree with Cturbo. I was told by TPC to keep the pop off valve in place but stack washers under the spring to keep it from opening under boost. We found out that the unit was still leaking at idle causing the system to take in extra air that was not being metered by the AFM.
With this leak fixed, the transition to boost is much smoother and the car has not yet stalled even with the lightweight flywheel.
You may need to put a caps on both pop off valve ports to ensure that the unit is not letting in air at vacuum.