What could be causing a cylinder to misfire? code 0306
crwdns2934249:0crwdne2934249:0:
When starting my 2003 3.5 altima, it runs very hard. the whole front end was vibrating. As i continued to drive the "service engine soon," light began flashing, but then went away. After driving for about a mile, my car was driving normal. When i got home i manually got the code by putting the EMC in diagnostic mode, i came up with 0306, which appears to be misfiring in cylinder six. What could be causing the cylinder to misfire? How should i go about fixing it?