Hey how are you
1- did the injector pulse come back or no or intermittent
what is the fault # P0300 .
2- do you have a scanner that can read live data ,what are the fuel trims,long term & short term at idle at operating temp ?fuel status : open loop or closed loop ,at idle at operating temp
3- check for intake vacuum leak on that bank that is misfiring ?
4- click on link to view wiring diagram , the injectors are pulsed by PCM, now u said you replaced splice 143 to 155 , the 155 goes to injector ,that is power wire ,now the other wire on that injector #8 , do you have injector pulse from pcm, Connector #C1 , Pin #4 on pcm plug
most of time it is a pcm ,driver issue,other words need pcm,if wiring checks out ,we need power on one wire and pulsed ground from pcm , what are u missing
Vacuum leak check ,best to ask them to do a smoke test ?
Please let me know & we go from there ,let me know If you can not see the diagrams
ASE Certified Technician