If it is getting air in the system FNQ it will be hard if not near impossible to start.
Phil is it blowing smoke?
EGR = Exhaust Gas Recirculation. Modern diesels use this as a method to meet emision standards.
I am thinking the system is not functioning correctly causing power loss. As the problem is not always there and not present under hard acceleration, a sick injector would be there all the time.
Some professional help may be needed on this one Phil.