A good ,quick test to check the fuel pressure regulator for leaks is to run the car to build up fuel pressure,turn the car off, then pull the rubber line off of the fuel pressure regulator.Then put a rag under the regulator where you removed the rubber line.
Then wait for a while then recheck it.If you have fuel leaking there, then the regulator needs replaced due to a leaky diaphragm.

Usually you will see fuel leaking at the regulator from the stem that the line attaches to.
This causes the fuel pressure to leak down at the fuel rail and thus takes time to crank and fire off until pressure is built back up.

Sometimes you get lucky and a little fuel spits out at you when you remove the line from the regulator, as no fuel should be getting past the diaphragm.

When you replace the regulator, you will need to loosen the fuel cap to relieve fuel pressure, then just remove the c-clip holding the regulator in, and pop the new one in and reinsert clip....done.