2000 Ford Taurus P304 Code

My 2000 Taurus has 124,000 miles and I am getting a P304 code. The car has a coil-on-plug ignition system. I had a major tuneup at 105,000. To date, I have replaced the spark plug and the coil. I disconnected the battery when when I replaced the parts and therefore reset the computer to hopefully get rid of the service engine light. However, I'm still getting the service engine light and I can feel the car miss ever so often and then I get the service enginme light back on. Soemtimes the service engine light goes off other times it stays on. I used a Autolite spark plug and a Borg Warner ignition coil.

Any help on what else could be wrong?