Tricia Tumele could be a fuel or spark issue. You changed the spark plugs but need to check the coils as well. Remember that the 04/04 RX 8 had a TPB about using different plugs then listed in the manual. Make sure your replacement reflects that. It also is having chronic issues with flooding which can get the catalytic converter to clog and fail. Have that checked too. As for possible fuel issues you need to check the relay, the fuses, and the pump itself. This is a great car but needs a lot of personal attention. Here is the troubleshooting guide from the manual which may help out. It’s a ‘05 which works for the ‘04 as well. [document|27011]