Crank relearn problems

Just finished rebulding my 6.0 for my swap,, the truck will never start upon first time cranking, as soon as I let off the key and try again it fires right up,, I ran into this issue before on another truck and I had to do the crank relearn with a tech 2,, this time I'm not so luck,, I can get as far as the relearn process, do the WOT and it only makes it to about 2500 RPM before stall/miss, no mater how may times I try it WILL not complete the relearn,,,, any suggestions??