Ours is an 04, LLY engine, we had #7 injector fail, putting it into "Limp" mode and had to tow, and about 6 mo later, the injector harness failed electricaly under heat conditions. Again towed. Been trouble free for 6 months and counting! Both problems are known issues with GM.
The earlier LB7 models had some issues with them as well, and they changed the injectors in 04 with the LLY.
I use Lucas fuel treatment/cleaner to help keep them clean. Advice from a mech friend.