2009 BMW X5 xDrive48i misfire - Cylinder 6 then 7 then 8.

[WhyIsThoseThings]

Check engine light came on; got the steering wheel vibration. Did an OBD check and got the P0306 error. Switched coil 5 & 6 and reset the error codes. Coil 5 showed an error. Replaced coil 5. For about 3 days the car ran like it was brand new and no shake. 2 days ago, check engine came on again with steering wheel shake. OBD check and the error migrated to P0307. Replaced coil 7. Reset codes and error came up on coil 8. I am going to replace all coils but I am afraid that here is another underlying issue. I also cleaned the MAF sensor just in case. I have read that it could be a leak in the vacuum hose leak too. Any suggestions?

[Ryan5034]

you should change the spark plugs as well, unless you know it's been done in the last 20k miles.