Please help I?ve done everything to chase down this code ? misfire number7cyl? and it runs fine and only comes on during cold start in the morning. I found a bunch of forum write ups that say this is a known problem on cold start, and I don?t know a fix. I talked to my tuner and there?s nothing he can do, I have a cold air and long tube headers cat less mid pipe. Light comes on and stay on all day, but if I clear it when engine is warm you can run it all day without a light, then a light first time the next morning when it?s cold.