My father has a 2003 HO. He called me yesterday and told me that his truck was stumbling real bad at idle like it wanted to die, and upon acceleration would hesitate as well. At highway speeds the problem would clear up. It has been real hit and miss. Is this computer or electrical. Or a known problem? It a 2003 3500 SRW HO automatic 48RE

 

I would try running a big dose of diesel fuel additive to clean the injectors. Did the truck started to act up after refueling? If so also change the fuel filter and find a different fueling station.
If the problem still persists have your Dad take it in to have the injectors tested.

MikeyB