2004 Mazda RX8 car starts but I keep getting a P0320 coil m

I recently replaced the coil packs and spark plugs and wires. I keep getting a check engine light and when i check the code it is the same one (P0320). I checked the fuel pump by taking the gas cap off and listening and it appears to be functioning so i started the car then pulled the fuses under the hood and let the car die from lack of fuel. I then tried to restart the car a couple times and then replaced the fuses and the car started up so i know its not the pump. For a while I noticed a strong fuel smell coming from the car. while idling the car struggles to keep running and the idle fluctuates from from .500 rpms to 2000 rpms. Prior to all these problems I let my cars fuel drop lower than i ever have. Could this be a catalytic converter problem and how do I check that.