I have a 2007 crew 4x4 5.4 having problem with truck misfiring when pulling hills . trying to pull a hill it will only go to 4100 rpm 71mph thats it. Took it into dealer they replaced 2 3 5 coils. THE 2nd time in they replaced 2 5 6 coils dont understand WHY this is happening any suggestions

 

This is exactly my problem. I inherited this 2005 Lariat with 138K and it was running perfectly in Florida. Brought it to TX and 5K later this stuff began. Ford dealer changed one coil for a bunch of money and it ran perfect for about 5K. Then it became erratic, temperature sensitive, etc.
Local mechanic changed fuel filter ($20) and improved considerably, but under load, it would misfire some. Started research on this forum for the plug problem. I am going to run two tanks of gas with sea foam and then change the plugs to the Champion one-piece plugs. They may not last as long but should not break when removed.

 

Very common problem with these trucks, just do a search and you will find lots of threads about this, and I hear those Champion plugs are not the best, your better off sticking with stock. I have a buddy who changes out his plugs every year to avoid the problem with the f150's.