96 Cirrus misfire. help please

I am trying to fix my girlfriends car. It is a 96 cirrus with a 2.5 v6. The check engine code keeps reading cylinder 4 misfire. I have replaced plugs, wires, distributor cap, and rotor and it is still misfiring. I can't figure out the problem, i noticed that i could hear the sound of sparking coming from the cap, don't know if thats normal.

I would check the injector on cylinder 4 that could be it. if you dont know how to test it. It would probably only about 30-40 dollars for a new one.