So lately my oil pressure light has been coming on, and my mechanical oil pressure gauge has been reading about 22psi at full operating temp. I run Amsoil marine heavy duty oil. It's not due for a change though. Is the pump worn out and replaced, it would be my guess. My Cummins manual says the minimum pressure rating is about 32 psi if I recall correctly.

 

22 psi should not turn the light on. I would check and clean the connection at the sender and maybe replace the sender if you are worried about the light. The sender in these trucks is very tempremental at best. Where is your mechanical gauge getting its pressure reading from?

 

I do have a felling it could just be the sensor like you said because at an idle it drops to nothing like the truck isn't running, but go right up where it belongs once I give it a little throttle. I have my mechanical gauge tapped into the hole on top of the oil filter next to the line for the turbo.

 

That is a bad place to take the reading from. That ia a regulated port the pressure won't be accurate there. Try removing the stock sensor and hook up the mechanical gauge up there.