Rattle in coast

[Slow Six]

Early 03, 305 HP version, 6 speed. There is a very obvious rattle in the engine when I am in a "coast" position such as driving slowly through a parking lot going from light throttle to no throttle or vice versa. It is also noticeable at other speeds any time I go through a change from throttle to coast to no throttle. It is hard to describe but it is similar to a timing rattle. It has been there for a long time and doesn't seem to be getting worse, but it is a concern. I have changed the FCA twice. It seems to be a little better for a day or two but than is the same again. I talked to a diesel shop and they think it is injector(s). I do not really want to spend a lot of money again on injectors as they have been done once. The engine starts and runs good, pulls good and mileage is consistent. There is no smoke at idle. I would like to hear from a tech or any one who has had this same problem. TIA