Emission test said OBD not ready on your 1998 Ford Explorer and you need to do a drive cycle What are the parameters for a 'driv?

Ford has a big long list of things for a tech to accomplish this with a scan tool.

To do the same thing on your own As long as the car (Explorer in your case) works correct, otherwise you are going to need to pay Ford.

Let the car sit over night.

Key on and cold start without any delay and turn on head lights, rear window defrost, AC or Heater full blast. Allow to idle for two minutes.

Shut off all the accessories turned on and pull away at about half throttle if possible. after the first acceleration, use accessories as desired.

Go for a half hour combined drive through town and at least 15 minutes steady throttle highway speed.

Allow 2 minute idle before shut down.

This will hopefully get all the self check functions done and you will pass emissions testing.