They are only accessible from underneath - vehicle has to be on a lift since the engine is transverse mounted and three of the plugs are right next to the firewall (passenger side).
passenger side plugs- through the passenger side wheel well driver side plugs- under the hood
There are 6 plugs 3 are on the driver side and 3 are on the passenger side alone with the coils
For both 4 & 6 cylinders, they are on the passenger side of the motor. Follow the plug wires to the plugs in the side of the engine.
The firing order for the spark plugs in a 2000 Mazda B3000 start on the passenger side. The order is as follows - passenger side front, passenger side center, passenger side rear, driver side front, driver side center, driver side rear.
Disconnect the battery, remove the spark plug cables, boots and spark plugs from the driver side, and put in the new spark plugs and replace everything. Lift the passenger side on a jack, remove the tire, from under that side of the car, remove the spark plug cable, boots and plug. Replace the plugs and everything else, then lower the car.
firewall passenger side just below the spark plugs
Under the throtlle body / upper intake manifold which needs to be removed to access the 3 spark plugs on the driver's side. The other 3 are on the passenger side of the engine.
It is screewed into the head between the first 2 spark plugs on drivers side. If heads have been switch around then it will be between the last 2 spark plugs on the passenger side.
If your Explorer has ac, you have to remove the passenger side front wheel and then the wheel well flap. The job of replacing the spark plugs will then be much easier. Sounds like a lot of trouble, but well worth it.
passenger side 2-4-6 driver side 1-3-5
There is a long black item on the passenger side of the engine. That is the coil. They are under it.