#8 is a guinea pig... anything from low fuel pressure, clogged fuel filter, bad programming etc... could cause that one to fail. Just like CSI said about the dead end fuel system.
As for #2 that's something to address.
Since it's injectors on the same bank, at opposite ends I would certainly check the UVC harness, but usually ajoining cylinders fail when the harness goes bad.
Check all wire connections on the outside and inside of the driver side bank.
Here is a video for you.
Under Valve Cover Harness