2000 GM Engine misfire

I get a Po3o8 code which is number 8 misfire. I changed the plugs and the coil with no change. It is a steady miss, worst when idling in gear. Would this code also indicate a possible injector problem? Any ideas on the next most probable cause?

I'm not 100%, but don't think it's the injector. I'd trace the wiring back from the coil, check for any breaks/damage to the wire.