I have a 2010 F150 5.4L with 200,000 miles. Almost all HWY.
I noticed the truck had a bit of a rough idle, so I figured it was time for new plugs....this would be my second set. No codes thrown.
So I go to Ford dealer and have the plugs done. The Service Advisor tells me that they made a mistake and put my new plugs into the wrong truck..that didn't need plugs...but they could take them out and put them into my truck. I figured it would be ok since they were only in the other F150 for as long as they figured out it was the wrong truck...so no harm..
Well....this is going to sound ridiculous, but my truck is all kinds of screwed up now.
I had to drive about 300miles the next day and I noticed these issues AFTER the change.
1) Gas pedal is stiffer than it was. Takes more pedal to maintain HWY speed and truck has a hard time cruising over 60mph...I'm having to push a lot more to get her to run faster. Acceleration is worse and there is a power gap and bogging feeling from 20 -50mph.
2) The brake pedal is stiffer as well. The pedal feels closer to me than before and takes extra effort to get truck to stop. Why this is happening I have no idea. At lights I have to push harder to keep the truck stopped...
Combine these two and the truck is radically different to drive than before. It feels like there is this restrictive pressure building up that is keeping the truck from both running and stopping....
I took it back to the dealership and they have no other answers except that this is truck with 200.000 miles on it and they maybe I should have the fuel injectors cleaned. I compromised and had the throttle body cleaned, but that hasn't helped.
I need my truck to run the way it did before this spark plug debacle...I plan on a new F150 in about 6months, so I'm hoping this can be resolved..