Hi, recently replaced the fuel pump (within the year) but I dont know what brand it was , I know it was expensive. But everyone keeps talking about the "nut kit", exactly what is this? Sorry for the dumb question !

 

Steph.. sorry for your troubles ..
The 'nut kit' is a short section of fuel lines inside your intake manifold which get brittle and sometimes crack over time.
If your FP press test show pressure dropping rapidly after pump is off, the there's a good chance that either those lines or the fuel pressure regulator is leaking. The third possibility is that the Fuel pump check valve isnt holding Check valves allow flow only one direction.

There is a separate pressure test for that at the fuel filter location but you have to kluge up a connection to do it.