I had a diagnostic for a check engine light of my 04 250 Diesel. It said EGR Valve, so I changed it and the problem continues. Blue smoke from the exhaust and the truck has little power when you start and going up hill

See if this link offers any insight:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-10.html#post1977241