Have a 2004 F 150 supercrew with 5.4 motor. Truck has been misfiring a lot lately. Went to a machine and he replace all the cores and sparkplugs. He told me that it is still misfiring with it is and I told me need to replace the timing chain and cam phasers. Any thought on this. Have 168,000 on the truck

 

I'd like to know how he came to this conclusion. Maybe because there's a lot of money in it for him. Do you have a check engine light on?

 

^^^ Agree

If you do not have timing DTCs, your timing chains and phasers have some more life left in them. Mine made it to ~ 200k miles before starting to throw timing codes and had to be replaced at 212k. But long before that, around 120k I had absolute hell with misfires before figuring out a solution. You might benefit from my experience in this post. https://www.f150forum.com/f4/5-4l-3v...6/#post3930018.

I'm betting your mechanic did a sloppy, half assed, quick plug change job. THAT won't work on the 5.4's.