Have you checked the engine oil level? How much cranking have you done since all these parts were installed? Did you re install all 4 of the little 1/8th allen oil rail plugs under the valve covers? How does the ipr pigtail look? Is the nut on the ipr tight? There is air in the high pressure oil system, and cranking is how you get it out. You can also remove the icp sensor, and pour oil into the oil rail itself. Lots of variables here. How do you have your gauge plumbed? One hpop line hooked into the gauge, and one line to the head? Or did you put a gauge into one of the unused ports in the external part of the oil rail?