BMW Repair: Misfiring, camshaft position sensor, o2 sensors

Question
Hi my question is how do I find out what is causing my 2001 325i bmw to misfire. I was thinking of changing the o2 sensors, when ever I turn on the car I look at the rpms and it goes up and down like the car is going to turn off. I have a diagnotic and it says that I have a misfire in bank 1. Please let me know how to fix this problem. Thank you. Semper Fi.

Answer
Edwin, O2 sensors are not faulty very often. At this point I would only change them if the vehicle has over 100k miles due to maintenance interval. I would spend an hour or two of labor at a reputable shop or BMW dealer to avoid unnecessary repairs. If the vehicle does this when the vehicle is cold then the O2 can be ruled out because the DME (engine computer) doesn't use them for fuel mixture adaptation until the motor is warm and the O2's are active.
Sounds like a camshaft position sensor gone bad. If it is diagnosed as such I would replace both due to a more current updated designed part available. Thanks for serving our nation.
-Evan