1.) How old are the plugs and wires?
2.) Have you checked the cap and rotor for cracks and carbon tracks?
3.) Have you checked the wires for cracks and damage?
4.) Have you opened the hood at night with no light and looked for sparks jumping or plug wires glowing?
5.) Have you used an ohmmeter to check the resistance of the plug wires? You should see about 2000 ohms per foot of length.
6.) Does it miss more when the engine is warm? If so, you may have a bad TFI
You need to put your car year and mods in your sig. It helps to troubleshoot problems to know what the car has and what year it is. It is not there so that we can spy on your secrets.