Try shifting the plugs around, look close at the one from number two. Does it look different than the rest? Next run a fuel pressure test, low pressure can cause a mis, especially when you are at higher rpm as the pump cannot keep up (35-45 psi key on engine off).
When was the last time the fuel filter was replaced? A partly clogged filter could also restrict fuel flow and cause a misfire. (Test the pump output, should get one pint in thirty seconds)
Lastly, run a compression test, high mileage, it is possible a valve is not sealing good and causing it to show a misfire in that cylinder or even a minor head gasket leak between three and four would show as a number three mis.
Tuesday, January 3rd, 2017 AT 4:41 PM