VG 2.5 Turbo Diesel Transit. Engine management system light on - no power?

My Transit has the engine management light activated on the dash. The vehicle has historically had an injector pump problem however this was fixed with second hand parts. Diagnostics show errors logs for both the Injector pump and a failed EGR Valve. The van won't get going much more that 50km/hr. And has no power beyond 2000 rpm. Could both of these errors have occured at the same time? Is it possible that the error for the Injector pump is an old entry? Would an error caused by the EGR valve cause the Engine to go into limp mode?