Another place to check--
The injectors have a plastic "T", with a o-ring and a line on each one. They are connected together. That returns unused fuel to the fuel tank. The plastic T can crack. GM sells the complete part for each side. They are held in place at the top of the injector with a small hair pin clip.
Chevy 04.5 LLY, 2X, shell, XDR, MikeL Heavy duty up-grade, 6spd, TransGo, deep pan, de-badged, 65 Gallon replacement Aero tank, LBZ-mp, Kennedy pump, shimmed, Pre-fuel filter, tow mirrors, BU cam, gauges, GPS, Sirius, bags, custom grille, fender vents, HD trans cooler- Curt front hitch, footwell lights, load lights, Studs, head gaskets.