'03 Kia Sprectra Code P0325 - knock Sensor mal

The car knocks or misfires only in gears 1 and 2. I regapped my sparkplugs and it showed some improvement but still happening. what should I do first as far as eliminating causes. Last tuneup in August 07. I have never replaced the wires that are attached to the 2 square, jelly filled containers. Any help here would be greatly appreciated.:confused:

replace the plug wires. the knock sensor code will not cause a misfire.