02 xlt with what engine?
Did you do it one wire at a time?
When you post a question like this you will want to include allt eh vehicle information.
Since your profile says 02 XLT I will assume it is a 4.6L V8 gen III explorer, correct? Because it could be a 02 sport which can have the OHV 4.0 or the SOHC 4.0L V6 or the sport trac which would also have the SOHC V6.
If you did it one wire at a time, I would go back and check that you used the correct plugs for your application, that they are installed properly and fully, the wires are clamped on to each plug and the seated in the coil pack fully.