Fuel Injector replaced?

I recently changed all my spark plug with ACDelco 41162, I also change all the coil packs with ACDelco wires, and also I only change one ignition coil harness backside of engine as well, note I was getting a p0308 code nothing else, but my car drives completely fine no flashing check light at all when it do comes on its solid and still my car drives fine no shaking or rough idle at all. I did check cylinder 8 plug it was clean no damage, I tried switching coil packs to see if it jump to another spot but no cylinder 8 it's stuck on, like I said before my car engine sounds completely good, so I plugged scan tool up too check the live data inside misfire #8 jumps from 0 then go up to 4 then back to solid 0, the rest stay at 0 only. I changed my plugs out due to having a misfire 6 and 7 then 8, that's when I did a full tune but after that 8 only showing, I checked all wires everything good. I ordered another ignition coil harness for the front side of engine hopefully that helps if not I will change out all fuel Injector. I need a diagram on what I need to do to replace injectors as my next step. Thanks