I have a 97 F150 with the 4.6. So I've been successful at eliminating all issues besides the cylinder 1 misfire. No other code follows this one. So, it has been causing the CEL to flash however, it only does it at idle or slow speeds. At normal speeds it doesn't flash. There is an alarming sound coming from around the area of cylinder 1. Sounds a lot like rocks in a milk jug. All the basic common things to check for, I already have. I had the valve cover off the other day checking, but didn't see anything jump out. The timing chain seemed to have a slight but of slack from what you could feel from under the valve cover. That's really the only thing I could see. The cam and rockers all seemed fine. The truck doesn't burn oil. It does smoke, but not horribly, sometimes not at all. Although you can definitely feel and know there's a misfire. It doesn't seem like a misfire due to the piston or any deep stuff like that, it seems to be near the top. I'm beginning to wonder if that chain has got too much slack and could be causing the misfire as well as the sound because it's slapping things because of the slack. Anyhow I did upload a video on YouTube to give a better idea of the sound. It's only doing this on cylinder 1. Nowhere else. If anyone has a clue, please inform me, thanks!