Fuel pressure regulator location needed

It is mounted at the end of the fuel rail and looks like the attached image. Your description sounds like the diaphragm in it has failed and the engine is getting extra fuel through the vacuum line attached to the regulator. It's not hard to test, locate the regulator and pull the vacuum line off, does it smell like gas or is the hose damp inside? Yes to either means a bad regulator. Replacement involves removing the fuel line and then the regulator bolts, It pulls straight out, Apply a small amount of clean fuel to the O-ring and push the replacement in, then bolt it into place and reattach the fuel line. I would replace the vacuum line as modern fuels tend to degrade rubber and it could start leaking.