Had this problem for a while now, several garages have looked at it, two of them diesel specific garages and nobody is able to pinpoint it. Problem is that when it is cold (typically below 0 deg C) or a bit damp out the truck will hesitate until it is somewhat warm. Usually for about 5 minutes or so when you give it gas it sputters a bit, hesitates and does not seem to have full power range. It feels like slight fuel starvation. Obvious stuff... Changed the fuel filter, air filter, filter on the manifold, had the ECM intake cleaned and de-carboned. They have had it on the computer multiple times and it does not appear to throw codes. When it is warmer weather it runs like a top. Obviously from my post i am not a diesel mechanic but one would think the garage would be able to nail it down. Still looking for answers, my latest google had me looking at lift pump solutions?? thx in advance for any assistance guys.