The 04.5-05 LLY engines had a problem with the injector connections where they attach to the injector terminals. Connector #2 and #7 were the problem ones. When this happened, the engine lost power and you were stuck along side the road.
The wires were pulled sideways, which loosen them. It was found that you could use an SHARP ice pick and push on the plastic connector to raise a dimple inside the connector. This made a firm connection and it would last.
GM had a replacement wire that required you to cut off the old wires and reconnect the new wires. This "Fix" was done to many vehicles, (parts were like $250), but many found it did not last and they had problems again. GM charged something like $500 to do this repair.
Another area where some had problems was the FICM harness where it is attached to the side of the alternator-- the sharp corner of the bracket cuts into the wires and shorts. Just raise the harness and place a piece of heater hose under the harness and tie down again. I cannot believe that so many people have not done this 2 minute fix and are waiting for a breakdown.
It was rare for LLY engines to have actual injector problems, unless contaminated fuel was run.
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.--- Jerry