Welcome to JustAnswer, my name is XXXXX XXXXX I'm here to help get your problem resolved. Ask follow up questions, thanks.
34psi at idle and 43psi with vacuum line removed from fuel pressure regulator or key on engine off.
Have you check for vacuum leaks by spraying alternative fuel around itnake, thorrole body, ect to see if idle changes?
Did you check fuel pressure?
What size engine?