When I did my 454 tbi swap, I put the o2 inthe 454 manifold in the same location as the 350 manifold.

The problem i am having is that engine shows signs of being lean (surge, good mpg) and blm is ranging from 100 to 120.
02 datastream looks normal. Sure looks like o2 voltage is showing richer than actual. Could my placement cause this.

I unhooked the o2 and drove it in open loop, and it is much smoother.