Volvo: 2000 volvo s70 misfire, 2000 volvo s70, volvo s70

Question
I have a non-turbo 2000 s70. The check engine light sometimes blinks and sometimes stays on. The car runs rough. The code indicated a misfire #4. I changed all 5 plugs and the situation continues. My question is, if the number 4 plug that I removed was dry does that indicate an injector issue or does the injector not function if the coil is bad? Why does the check engine light sometimes blink and sometimes stay on? Any advice would be greatly appreciated. Thanks!

Answer
Andy,
If the plug is dry run the car and remove the wire to that injector while running to see if you can feel a difference. If there is a difference then I would say the injector is firing. They moving the coil from # 4 to # 1 see if the fault follows. Run a compression test making sure they are all close or with say ten percent ofeach other.
The light flashes because it is finding a fault as it is happening.