I have a basically stock 5.9L with 52k on it. Serviced it regularily, Changed oil every 5k, and just had the fuel filter replaced a few thousand miles ago per the dealers recommendation. And I might add that also it gets Redline 85 Plus diesel fuel additive at every tankfull.

So my question is why should I be having rough starts in the morning? And in the summer of all times!

And in rough starts I mean once it turns over it stumbles a bit, coughs, farts, and eventually I get a smooth idle in a couple of minutes. No problems getting it to turn over though. One twist and away it goes. It's just never sputtered along like it does now.

Is there anything additional I should be doing? (or aware of)