I just found out that my Number 4 cylinder is not firing. Once it cools down we are going to pull the plug and wire and check both. Could it be the opti? I heard that most the time when it goes out its the #7 cylinder.

Car is a 97 Camaro Z28 with an LT1.

 

Have you checked the PCM (computer) for codes? It may be indicating a faulty injector circuit, or it may see from the misfire counts that other cylinders are having a problem as well. You do need a scanner with "GM Enhanced Parameters" to check the misfire count by individual cylinder. Pull the wire off #4 and see if you are getting spark.

A single cylinder misfiring is seldom due to the Opti, and I've never heard of the Opti's causing a problem "most of the time" on #7.

Check the plug wire from the Opti to #4 plug. Look for corrosion on the ends. Pull #4 plug and look for damage. Pull the injector harness connector off of #4 injector, and check for +12V on the pink wire with key on/engine off. If you have +12V, put a 'noid light on the injector, to make sure the PCM is providing the ground required to fire the injector. With the connector off the injector, you can also check the resistance across the two electrical pins, and verify the injector resistance is in the range of 12-15ohms.