Where is fuel regulator of 04 Ford Freestar location?

It doesn't have one. The pressure is regulated by the fuel rail pressure sensor sending a message to the pcm which limits the fuel pump speed to 70-100%. It is located on the fuel rail just behind and to the passenger side of the intake system. Two 5/16 bolts hold it to the rail. Remove the plug from the back and slide off the vacuum hose before removing. A good bit of fuel may be released.