Another rough idle & hesitation question from newbie

[VolCTD]

OK, first here's the truck; 2003 2500 CTD 4x4 auto trans all stock with 87k miles.

I've read several other posts about folks rough idle on a cold start and I have a similar problem. It also wants to drop RPM's when I let off the pedal and it drops below 1000 RPM. It has died several times going down the road on me. It also has the hesitation problem from a dead stop. Sometimes the rough idle will come back after a long haul and you come off the interstate. But for the most part clears up after the truck is heated up really good. I've got to get this fixed as I just bought a 5th wheel and can't say I want to be driving down the road and it die on me every little bit.

I add PS to each tank as well as 2 stroke oil every other tank. I bought the truck used in July and they replaced the lift pump before I picked it up with the new "in tank" one for me. Since then it's been back and had 3 injectors replaced, the water pump (not related), and the cam sensor replaced. When they replaced the cam sensor everything cleared up for about 3 weeks and now it is all back again. I have checked all the wiring I thought might have been frayed but nothing so far.

The next thing I was going to try is a new FCA. Would this be the next best place to look?