Consistent misfire on Cylinder 5 causes?

[mikesz]

I have a 99 base USA spec car. I have had the car 5 years. I probably put 1500 miles on per year. I am getting a consistent misfire on cylinder 5. Consistent being the last 2 days. Last year I replaced the coil packs with with BERU upgraded mounting units. About 3-4 years ago I replaced the spark plugs and tubes. I am not sure I think I used NGK plugs. I change the oil and replace air filter every spring. What could be causing the misfire? I ordered another coil pack and was going to replace the #5 spark plug just to be on the safe side. I am thinking it might be the wiring to the coil pack. I found plug with wiring for $35. Anyone have any ideas what it could be? besides coil, plug, wiring?