Cyl contribution test told me cyl 5 and 8 are off balance. Cyl 5 the buzz test was weak, hard starting, and runs poorly. What to do?

 

Pull your valve covers and check your harnesses. I would start there. Good luck

 

If you have a new/recall-replaced CPS, they will ALWAYS set a fault for #8 injector. They are junk and can't pick up the signal window. Some have been so bad the truck runs poorly becasue of a bad CPS.
Many times it's #3 and #8 in a CCT with no real issue with either injector.

Best way to tell if injector is bad is to swap it with one in another hole and if problem follows then you know for sure it's the injector.

Good luck.