First of all, kudos for helping out an Air Force Chief, second you may want to suggest checking compression to see how are the cylinders doing. If you still think that there may be an issue with fueling system or EGR, check out the diagrams and OEM workshop guides on all the potential faulty elements https://www.carmanualsonline.info/nissan-300zx-1984-z31-engine-fuel-and-emission-control-system-workshop-manual