My '96 Formula had been missing when it rained or there was heavy humidity. It would stop missing when the car warmed up. Finally I got the P0300 code. I could drive around and the SES would go out, until the next time there was moisture in the air. I figure coil or wires. Finally it rained and the light came on again. Another P0300, and once again it went out. After another rain, another light, this time it was for a misfire in #7. Light went out again. A couple days later, when I started the car, I could hear the arcing. I opened the hood, and the arcing seemed to come from # 5 or # 7. I shut the engine off, and reached back to #7, but the engine was to warm to touch the plug wire. After it cooled off, I reached #7 and the wire fell off the plug, or so I thought. I jacked the car up, put a jackstand under it, and crawled underneath. Much to my surprise, the wire was burned completely off at the plug connector. Fortunately, I had an old wire and replaced the burned wire with it. It cured the problem. It's rained since I replaced the wire, and no miss. So, that means ONE wire or plug can cause the P0300 code. I think someone else also posted that they had also found that to be the case.