Q: Expedition misfires going down road at about 40mph. It will eventually "punch" through and take off smoothly at faster speed. Che

Hello, thank you for writing in. The first step is to have the vehicle scanned for diagnostic codes. Then you can take that information and find out what is causing the misfire. Without that information it is a guessing game. The most common reasons for a misfire are spark, air, and fuel. There are several sensors that can also cause these symptoms. Think about any recent work you have had done. Consider the last time you had the spark plugs changed and examined. The fuel injectors can also become gunked up and need to be cleaned. The issue may be general maintenance related, or it may be something more intensive. More testing will need to be done. For further help resolving the issue, contact our service department to schedule an appointment.