I've been working on AL headed engines a long, long time (30+ yrs.). I've done my own Duratec plugs 3 times now. NEVER EVER use anti-seize on spark plugs. Firstly, it impedes the transfer of heat from the plug to the head/water jacket. Secondly, using anti-seize causes an incorrect torque reading. The torque per the Ford manual is a "dry" torque. Using anti-seize gives a false reading.
Spray with WD40 or Liquid Wrench each day for a week. It will also help if you attempt to remove the plugs when the engine is warm, but not hot. Be very careful and use the correct tools. You should be able to start them. If you can get them started, but they're still tight, turn them in a little, then out a little, and on and on. Don't forget to blow out the plug wells with compressed air before removing the plugs. This way no garbage falls down in the combustion chanber. Use a properly calibrated torque wrench when installing new ones and you shouldn't have this problem again.
