Engine is hard starting

Check compressions hot and check fuel delivery system, check for contamination in the fuel. I would be looking at the lift pump and the high pressure pump. Power strokes have a habit of failures with these items.
You need a good truck shop that can diagnose it correctly for you and give you a bid.

Yes, Cummings are great engines with very little issues.

The first thing you need to do is verify fuel pressure with a gauge, you can also unscrew the lid on the fuel bowl and make sure it's full of fuel. Jeff

Things that can hard start, Fuel pump, listen when you first turn the key to on, not start, just on, you will be able to hear it run fo 2-3 seconds, Idle air control valve, it's bolted to the throttlebody, TPS, also on the TBI, Vacuum leaks, clogged PCV, after you start it, check for vac leaks like this get a can of spray gumout, spray the vac lines and maniflod area, when the idle changes, youve found the leak! You want the engine running and spray on the outside but do direct the stream onto the hoses, if it is a vacuum leak, the engine idle will change speed, then you have detected a leak, repair the vacuum leak and see how it runs! If that doesnt do it, you may need a new idle air control valve, it's bolted to the throttlebody
One last this is the engine coolant temp sensor, this acts like a choke for fuel injected vehicles.

Good morning,

Did you check the fuel pressure to the fuel rail? It will cause a extended crank time for the engine to start.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Can you check for spark at the plugs?

https://www.2carpros.com/articles/how-to-test-an-ignition-system

Did you also check the battery to be sure sufficient voltage is available for starting?

https://www.2carpros.com/articles/car-battery-load-test

Again, a video of how it sounds would be good so I can hear what you hear.

Roy