My 97 mustang is running rich and I dont know why. I have changed my o2 sensors and my spark plugs and my fuel pressure is in the norm. I dont know what else to check. Someone please tell me what else could be making my engine in bank one and bank two be registering rich. I also have cleared my codes after o2 and spark plug change and my check engine light came back on after a few hours and my rich codes were back. What should I do?