I am getting codes for both cylinder banks running to rich and a code 300 engine misfire. Are the problems Opti related?
I can really tell it is running rich I can smell the fuel when I first start the engine and revving the engine lets off some small back fires.

 

When you start the car does it crank unusually long? Does the amount of cranking change depending on when you start it? Like suppose it was running and you shut if off and come back 5 minutes later. Or if you let it sit for an hour, how long does it take to crank in both cases before it fires up? Check the FPR vac line to see if it's wet.

You could look for dead cylinders a couple of ways. Pull one plug wire off at a time but that's hard to reach. You could check the exhaust manifold with an infrared thermometer or you could use water in a spray bottle. You could pull an injector plug one at a time.

If it turns out you have a dead cylinder, don't run it long. Souping can scratch a cylinder.

An inline spark tester is easy to use and will tell you if you have a cylinder dead due to lack of spark.

 

It starts up fine and idles fine, the engine only seems to misfire at close to WOT or at WOT most of the time above 3,000 rpms. I am also getting a code 441 which is a malfunction with the Evaporative emission control system

 

Probably o2 sensors. Mine did the same thing. So I put in a new opti. That wasn't it. Just ended up being an o2 sensor. I would try that before spending all the money on the opti spark.