for a while now i have had a dtc of p0308. i have changed all plugs, replaced two coil packs, and run a compression test. code still showing and truck is running badly and getting worse. i am out of ideas. any help would be appreciated. i have researched a little and noticed that these engines have had issues with burning valves. could this be a similar situation?

 

Cylinder #8 is misfiring which may be due to a bad coil (still),
FF