I'm a newbie as I just purchased an 05 FX4 with the 5.4 a couple of weeks ago. Five days after I bought it all the sudden lost power and the little"wrench" light came on in the dash. I pulled off the road and shut it off. Let it set for 30 seconds and then started and ran normal. It was fine for a week but today it did the same thing. Shut it off and started it back up and it was fine. From what I can tell from the owners manual it goes into limp home mode. Anyone know what is causing that??

 

Well for starters goto a local autozone or advance auto or even the garage and get the code read and look it up to see what it says.

 

Check codes. Sounds like a bad throttle body though.