I was trying to install an A/F ratio meter last week end and noticed that the O2 sensor is not hooked up and the wire for it is nowhere to be found ( the wire out of the o2 is there but the wire into the harness of the car is missing). The car does have a header. It smells like it runs really rich but when i checked the spark plugs it looks like its burning fine. I don't know if its the header that causes it or not but it really doesn't have any power till it gets past 4000 rpm. Up till 4000 rpm it seems like there is no power. The cat has been gutted and the exhaust is 2.5in with a flow master 40. I don't think there is any restrictions in the exhaust causing the problems. My car also has a K&N air filter kit. I have checked my maintenance manual but can't seem to find where the o2 is supposed to go. I can't find the connector anywhere. So I guess the question is where can I hook in the o2 sensor. I think that might be whats making it run so rich. Also when I first got the car the TPS wasn't hooked up, I plugged it back in and the idle problem went away. Any help on where to plug that o2 in would be awesome. I hope that will help with the low end power problem also. Thanks for reading this guys.