I would suggest replacing your plugs as they are pretty cheap and are crucial to how your vehicle runs, also they can give you better fuel milage and increase hp… 

Spark plugs are pretty easy to remove. The first thing to do would be to remove your plug wires or coil packs from the top of your engine (assuming you have a 4 cyl.) (Note they may be under a cover). your coil packs may be able be pulled out from the cylinder head or may need to be unbolted (most likely a 10mm). once your coil packs are out you will want to put a spark plug socket down the hole with an extention and ratchet them out. Once the spark plugs are out just put your new spark plugs in and re-install your coil packs in the order you removed them and replace your cover. Easy as that!