misfire and stabilitrak off

I hope someone here can help me out. I have 2013 Silverado 1500 LT with 160+ and she's been acting up the last couple of weeks. The check engine light came on throwing code p0305 which is a misfire in cylinder 5. So we replaced plugs, wires and coils on all 8 Cyl. Now it will run fibne for a few...