If it has the coil-on-plug design, it could be coolant dripping on the coil. There's a bulletin on it.
a bad wire or a bad coil to cylinder 5.
P0304 : cylinder number 4 misfire.
P0306 Cylinder 6 Misfire Detected
Trouble code P0301 means: Number 1 Cylinder Misfire Detected
The most common reason for a misfire is the ignition coil that is connected to the sparkplug on top of the problem cylinder.
I had the same problem with a 1999 Expedition and it was a bad plug. Ford had a problem also with the plugs blowing out. It cost me about 1200.00
# 5 engine cylinder - misfire detected
I have a 2001 Prism, and all i did was replace the spark plugs, and reset the battery it went away....
Trouble code P1301 means: Cylinder 1, misfire detected
According to Haynes, this represents a misfire in cylinder 6.
Trouble code P0304 means: Cylinder 4 Misfire Detected
Spark plug, plug wire, distributor cap. Any one are more of what I have listed could cause a miss fire. #7 cylinder will be the last spark plug in the rear of the drivers side head. Didn't know if you new are not.