Low Pressure 2006 Nissan Xterra Recent Replace of Timing Chain Guide

[Surfschnauzie]

Need some help here. I recently replace the timing chain guides, the main tensioner and all of the chains, oil filter, spark plugs, on my wife's 2006 xterra. I was able to get the car to start and it sounds relatively fine, but after warm up the oil pressure drops really low and the oil light will come on. I suspect it is the oil gallery, but my wife does not recall having oil pressure warnings, which is completely throwing me off. The timing case had quite a bit of sludge when I opened it up. There are no external oil leaks. We knew that the car needed to be fixed because we could hear the broken main timing chain guide (which I confirmed when I opened it up). I get P0011 and P0021 codes after the repair. Is there a special seal located on the cam sprocket vtc cover that is not listed in nissan parts? I did replace 2 seal rings that were partially metal in that area near the same cam under that cover and were on each side and the rubber seals near the cam shafts. (i believe the lube up the secondary timing chains) Please help.