Cheech1419

I have 2015 chevy 2500 with the 6.0L gas. The truck runs good but after sitting for a day it struggles to start. It's hard to explain. It has a good crank and tries to turn all the way over but struggles for about 5 seconds or less. I have no check engine light and no codes currently. Truck has 131000 miles. I'm at a lose and I'm thinking maybe a fuel issue but not sure. When I cycle the key before start you can hear the fuel pump turn on and off. After starting it, and the struggle, it runs like normal and if I drive it or just shut it off and start it again....it starts perfectly normal. Any help would be awesome. Some codes I had before the issue was the Mass air flow sensor (replaced it) and an EVAP code (changed the fuel cap and the vapor canister solenoid)