What would cause a misfire on cylinders 6 & 8?

a misfire is any imbalance in power impulses that the computer sees. 6 and 8 are not neighboring cylinders so that eliminates a head gasket. if you follow the plug wires back or look at the firing order to see if those two are companion cylinders, you could eliminate or confirm a spark issue. but looking at the parts list i see that it is a DIS (direct ignition system) rather than a coil pack that can fire two cylinders at the same time, so i dont think a spark issue will be the issue.