Why did you swap out the HPOP? The 05-07 HPOP's very rarely fail, so it's got me curious. Also, did you swap out the STC connector for the new design one-piece STC fitting? Finally, you might want to double check your IPR connection by measuring IPR%, ICP demanded, and ICP using a diagnostic scanner to determine what pressure your HPOP is putting out.
PS. When you take apart the high pressure oil system, it takes a while to purge all the air out of it and takes several cycles of cranking and resting the starter to get it to fire.