installed? FYI - although it will be a PITA, pull the fuel rail, pressurize with air and submerge in some water. Air leaks will be easy to spot. Other option is to pressurize the rail while still connected to the fuel lines and check for leaks.
Either way you do it - a plenum re-pull is in your future. Also be sure to well lube to the injector o-rings before reinstalling into the rail. I like to use petroleum jelly.