Had the dealer look for a code and nothing comes up. 2003 ram 3500 diseal. Only when pulling out from a light sometimes when sitting still it stumbles and then picks up. About a yr now runs great top end. All filters and service complete

 

Had a similar problem on my 03 2500. Turned out to be the fuel pump regulator (or something like that can't recall the exact name) replaced it no more stumbling.

 

Probably time to change out the FCA.