The fuel pressure regulator on a 2000 Grand Am with 2.4L 4 developed a small fuel leak at the fuel pressure regulator located at the end of the fuel rail. I understand this is a common problem with these engines.

I replaced the regulator with a new one, but the engine now idles rough and hesitates off idle. I notice when I pull the vacuum hose off the top of the regulator, fuel flows out the top of the regulator at the vacuum line connection. I didn't expect to see fuel on the vacuum side of the diaphram. Am I correct in concluding my new pressure regulator is defective and fuel is being drawn into the vacuum line?

You are correct, no fuel should ever come out of the vacuum side of the regulator. It'* bad. . . again.

Okay. That will be regulator #4 on this car (that I know of).

Maybe switch brand of part you are getting.