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.