Your problem sound like fuel presure. once the truck is running fuel pressure has been built. after it sets for some time the presure bleeds off and the engine has to cranck it"s *** off to build enough fuel presure to start. Using ether just speeds this process. The truck is sucking air from some place..Hope this will help ya.....

 

could be at the transfer pump mine was at the electrical conection were its rivitted to the top of pump thats were the air leak was

 

It's either a low pressure fuel leak (lift pump to the injection pump) or a high pressure leak (injection pump to the rail, #4 injector line is leaking, pressure relief valve, connecting tubes to the injectors, or injectors themselves). I'm gonna guess, that the connecting tubes need to be re-torqued.

What did you end up doing?

 

I bought an 03 for 8k as a donor truck for another project. the motor ran fine when i bought it. had to replace the front axle and luckily found one for $150! sold the junk one for that!
5th gear makes noise and now I trying to figure out whats with the motor. see my post (03 cummins idles high wont start hot) if anybody wants to read the problem.
Unless you like wrenching and are well educated in CR's, walk away.
I personally dont like the thought of the ether because you dont know how much its been used.
Anyways patience is a virtue and you get what you pay for...