The EGR cooler/valve are known to have problems. Why not just delete? Kits are readily available and you can update the problematic oil cooler at the same time. The parts for this are less than $700, and you can do it yourself with directions. Keep the injectors happy with on-time oil changes and fuel additives every other tank. These motors are all about maintenance, but keep them happy and they will return the favor. A healthy stock 6.0 will out pull a stock 7.3. If you want to hop it up, go with the 7.3.