Fuel pressure low

As said above make sure you change all the fuel filters. You should have two on that motor and possibly a Davco as well. If those have all been changed start checking the fuel lines.

You can do an injector test to see how they look but i doubt your idle stall would be related to an injector.

Start with the basics and go from there.

 

If done right an injector test will not catch an electrical issue if it’s sporadic but it’s a good test to use.

Based on what you said so far definitely check all your fuel lines. It sounds like air may be getting into the lines. 1 bad injector wouldn’t cause a stall at idle.

 

When you turn the key on what you hear is the electric primer pump not the high pressure pump. They are two different animals. Are you sure your it was your high pressure pump replaced and not the primer pump?
This picture is a high pressure pump.