early to late HPOP swap 6.0 powerstroke
 

So I have a 2004 late build 6.0 powerstroke and while I was doing headgaskets I swaped out the early style HPOP to the late style with new branch tubes and all. I used the IPR for the newer pump and now im having starting issues, lack of power, and awful fuel milage. It runs rough when you first start it but when it warms up seems fine. Its fine when driving down the road empty but with a load is when is gutless and awful fuel mileage. Any Ideas? Its running a 58v ficm new injectors and 28-32 psi boost. I tried swapping in an 05 ecm and it ran absolutely beautiful with tons of power but nothing in the dash would work because of the old instrument cluster.