snowwhos

I have a 1999 Legacy GT 2.5 non-turbo and have around 164k miles on the car. Just yesterday my engine light came on and checker said it was a p0304 #4 plug or wire misfire. Is everyone with this problem having bad injectors or should I start with replacing the plug and wire. Any input would be help full. Ps-after resting the code, this light comes on after a few drive and then starts flashing under acceleration then stays stead while driving.