[bigmoe]

I wouldn't walk away from the Gen IV motors with afm. The Gen IV's had a lot of improvements over the Gen III including more stock horsepower. There's a lot of them out there working well. I got a good deal on a low mileage Gen IV 5.3L so I'm not worried about the AFM. I just deleted it in the tune.
If it's a concern you can always do a delete kit with a performance cam. A stage one kit can add 68HP.