My 2010 ford f150 5.4l with 155k started to misfire and shake while idling. I took it to a local shop and they refused to work on it and suggested taking it to the dealership.

The dealership says I need a timing chain job, phasers, and new spark plugs. The job is quoted at $4400 for the timing chain job and phasers, and then $993 for the spark plugs plus an additional hour of labor for each one that breaks. I thought about just replacing the spark plugs only but the technician said if there is a timing issue the spark plugs are likely to break again.

Any advice would be greatly appreciated as I do not know much about trucks. Thanks