2001 Mustang GT w/125K miles. New plugs and coil packs and found the problem.

5K miles ago, cylinder #3 threw a spark plug. A local shop threaded, tapped/inserted a new thread. Didn't have to get new heads.

Now, car just started misfiring and my scan tool showed a P0303 cylinder #3 misfire (same cylinder where car threw a previous plug and I had repaired).

Today, I pulled the spark plug and the thread insert is attached to the sparkplug (see pics).

To fix, what are your thoughts? Do I...

Help - Have a P0303 misfire