A dirty fuel filter will drop fuel pressure. Try a can of Techron Fuel Injector Cleaner in a tank of gasoline. A 5 psi lower fuel pressure doesn’t seem enough to be causing your problem. I would expect to see such a problem, possibly, under hard acceleration, not at idle.
Haynes or Chilton’s Repair Manuals are sources of instructions on how to check for fuel pressure, with vacuum connected to the fuel pressure regulator, or not connected. It will, also, have the specified fuel pressure values. You can acquire such a manual?