Originally Posted by robert ray69
I`d try a sparkplug hole thread chaser before bringing it to Ford. I had a plug giving me trouble and the chaser cleaned the threads right up. If you go this route here`s a tip: Put grease on the chaser to catch any shavings and use a shop vac to suck out any the grease didnt catch.
x2. I always have to do this on the middle one on the passenger side.