If they've never been changed they are likely the sucky ones. You can buy a tool to get them out yourself but it's still a *****. I'd just take it to Ford and have them do it honestly... sucks but you'll be in and out and no danger of the car being down for days while you wait for the right tool to get a broke plug out.
2000 Mustang GT Steeda #0048 34k miles. 99 Cobra 4V swapped, FTBR IRS swapped, exhaust, tuned by James Gordon.
Just because I give you advice, doesn't mean I know more than you. Its just means I've done more stupid ****.