Regarding the vacuum line, no, the fuel pressure regulator's vacuum line (if it has one, depending on the engine) does *not* typically go to the PCV valve. It usually connects to manifold vacuum. The exact location of the vacuum port on the intake manifold will vary slightly depending on your engine (5.7L, etc.), so consult a repair manual or a diagram specific to your engine. The vacuum is used to control fuel pressure.
A faulty fuel pressure regulator can lead to various issues, including rough idle, poor performance, and even starting problems. If you suspect a problem, it's best to have a mechanic diagnose it rather than trying to troubleshoot the vacuum line yourself without a proper diagram.
