Raymond,
If it always turns and cranks well then it is not likely the solenoid in the electrical bay. That symptom would be no cranking or the engine shuts off while running, although changing that solenoid is a good idea anyway.
One thought (I always go for what is inexpensive first) would be to change your fuel filters and pay attention to the seating surfaces, they should be clean. Also if you have the prefilter pump unit with the vertical screen in a plastic bowl, be sure that there is no diesel seepage through the O ring seals used to seal the plastic body and no cracks in the plastic, it should all be dry. These are a problem area when the plastic ages or orings do not seal. Not sure what was used for a fuel prefilter arrangement in 2005.
Because this seems to happen after the coach has been sitting I was wondering if you might be getting an air leak at one of the filter seals that causes a fuel issue with some amount of air involved at start up. There could also be a filter that may be plugging up. This may be a more complex issue but filters are relatively easy to rule out....
Later Ed