4 or 6 cyl - it is not difficult to do yourself. Here are some pointers that will make it easy for you.
Four cylender is straightforward - easy as pie. Somebody please chime in about plug selection for the Ztec.
Assuming you have the 6 cylender:
Check the FAQ section of the main site & find the How-To. That will tell you most everything you need to know. Its not difficult to change the plugs, but there is a handy trick or two in the How-To that will make it trouble free & easy.
Plugs to get: Autolite APP764 Double platinum - VERY important to get those plugs as they are proven to be the best plug for the V-6. Gap them properly & treat them gently.
If you're changing the plug wires too, get:
1 - Magnecore
2 - Stock Ford replacements
3 - Autolite Pro-fit series
You'll spend extra for any of these three options, but for a trouble free car they are worth it - easy.
Happy Holidays!
Edit:
Click HERE for the How-To.