I didn't change mine myself, but the guy who did it gave me an overview. As I recall, it's behind the thermostat and timing chain. Definitely an advanced job in my opinion. While you're in there, you should probably replace the thermostat since it's an inexpensive part. I also replaced my main belt at the same time.
Off the water pump
how to check fuse for horn in a 1998 Pontiac sunfire
i would not recommend it
split the fob halfs and the battery will be on the backside of the board!
See stvndberryhill's answer under 1998 Sunfire horn relays. It is explained in great detail. The guy knows what he's talking about.
check this site------>
See stvndberryhill's answer under 1998 Pontiac Sunfire horn relays. This answer applies to all year models of Pontiac Sunfires.
Most likely, replace the ignition coil packs.
* Remove the front bumper fascia * Unplug the horn electrical connector and remove the bracket bolt
22 and 17