08 Avalanche 5.3 misfire codes and coils plugs and wires new?
What if it's not injector, plug, wire, coil
pack or vacuum leak....what's next
compression and remove valve
If you're getting misfire codes its unlikely its something inside the engine that you're going to be able to see. A compression check couldn't hurt although it's most likely electronic or electrical. Going through the wiring to make sure everything is tight and making good contact is time well spent on any older vehicle.