Trouble with cummins starting

When I go to start the truck in the morning( '98 5.9 12v cummins ) it wont start it just cranks. You have to try it about four different times before it will fire up. once it starts it shakes violently for a few seconds then it fine. When I start it after work it fires right up no problem. Any ideas appreciated

Air leaking into the return line at the rear of the head can cause this. They don't always leak fuel but will let ai into the line and prime is lost to the fuel injection pump.
Some of the mwtal lines has a seam leak that allowed this.

Thanks greatly appreciated. I'll take a look.