I've got a 94 4.6 t bird. After i got flowmaster cat back exhaust, my check engine light came on. i took it to autozone for their free diagnostic check. they said that my car was running too lean and that my o2 sensors are bad. at first i thought maybe it was just because of the free-er flowing exhaust, but now my car stalls at low rpms. Are the o2 sensors the probable cause? Also autozone told me that there are 2 o2sensors on my car, but Chiltons said that the 4.6 has 4, if anyone has any experience with this or has any suggestions, I would appreciate it.

It really sounds like the Idle Air Control Valve or MAF on your car is going bad. Do not let this happen! It causes the motor to run very lean and will end up destroying the motor. I know from experience. I didn't have any catastrophic problems. If I let it go on any longer it would have ended up destroying my motor. That wouldn't have made me a happy camper! The best thing I can tell you is take it to a very reputable shop or the dealer. Even the dealer is a very good source and they can be cheaper or the same as a shop. Just get your car there and let them diagnose it for you. I did like you and took my car to Autozone. They were wrong with their diagnosis. The dealer here where I live was cheaper on labor and scanning than some of the shops. There is just no way to tell what is wrong unless you do that. They will hook up the car and tell you what needs to be done. Tell them not to do anything parts wise. Good luck!

Bank 1 is drivers side and bank 2 is passenger side. Before you try to remove the o2 sensor, determine if you can reach the connector for it. The connector should be right behind the engine, between the engine and the firewall. If you go underneath the vehicle, you will see the wire run up to the back of the engine. These connectors have a locking clip. If you have a 1' long bore bit (flat wide blade for boaring holes) you can simply push the tip of the bit into the connector, pushing against the locking clip and then pull the wire down disconnecting it. To reinsert the connector you can put the tip of the bit in with one of the wire in the back of the connector then push it back into the mating connector. If you can reach up with a screwdriver or from above and unclip the connector, great... You can use a small crescent wrench or the appropriate open end wrench. 3/4" I think. Get your O2 sensor from AutoZone with a lifetime warranty (I think)     Chris Robertson

thanks for the great comments chris... take care