I have installed an airdog 2, and the FCA over the past 2 weeks because of the hard start. The truck starts fine in the morning when cold, but after running, it is hard to start. Sometimes I have to let it sit for 30 minutes before it starts. Took a trip with it this past weekend from Dallas to Del Rio Texas pulling a trailer with no problems. The hard start is random and I have not clue what is going on.

Truck is a 2007 5.9

 

Almost sounds like vapor lock. Can a diesel have that?