I was in a terrible traffic jam trying to enter the Daytona Speedway last month, and idled for almost 2 hours. The engine started running rough at idle, but seemed fine once off idle, and ran perfectly on the 125 mile drive home. The temperature never exceeded 190 degrees. When I got home, I pulled the drivers side plugs because I know number 3 gets oily. The other 3 were dry and slightly tan, but 3 was oil covered and crispy oil and hard black crud was down in the plug around the electrode, but the gap was open and fine. A new plug improved but it still is a little rough.


Does this sound like a bad valve seal? I have not as yet done a leak down or compression check and would do that before I tear into it. The oil issue has been on going, but the engine has run perfectly for the past few years and 10K on these plugs.


Any "magic additive" to clean a possible fouled valve?