I have a 2007 Ford F-150 4.6 liter v8 automatic with about 107k miles. I recently was driving and randomly got a code for misfire so I did a full spark plug job on it. It ran fine for a day or so after that but had a odd shake here and there when I would drive it even though the check engine light went away. So after the day or so the check engine light came on again I took it to a shop and they said it was the EGR valve so I changed that as well and then it ran fine for a few hours and then the CEL came on again and I just scanned it earlier and it says cylinder 7 misfire. What should I do or check?