stumbles on cold start and low fuel pressure?

The fuel pressure sounds okay, I would say the MAF sensor needs to be replaced which is common on these trucks with many miles. also, I would clean the throttle bore, here is a generic guide on how to replace the sensor and instructions below to show you how on your truck. I have included a video on how to service the throttle bore.

https://www.2carpros.com/articles/how-to-replace-a-mass-air-flow-sensor-maf

and

https://youtu.be/Z3LDHdS1upo


Check out the images (below). Please let us know what happens.

Okay, replaced MAF and cleaned throttle bore, no change. checked the fuel pressure again at the rail no getting 42 PSI. still thinking maybe, a weak fuel pump. any thoughts?

Yep, the fuel pressure is low.

Fuel Pressure (Key ON, Engine OFF) .................... 385-425 kPa (55-62 psi)

I would install an AC Delco fuel pump here are the instructions on how to do the job in the images below. Check out the images (below). Please let us know what happens.

Replaced fuel pump and still having issues with cold start and miss.

Have you done spark plugs, wires and coils? Sorry I didn't ask this earlier.