Nissan Repair: ecm, bosch oxygen sensors, nissan sentra xe

Question
Hello,

I recently began getting a service light on my dash. I got a code P0134, which is bank 1/sensor 1 oxygen sensor. Replaced it with a Bosch. Still got same code. Took to dealer. They diagnosed that is was the ecm going bad. My questions:
Should I check anything else before spending the 950 dollars(with labor)? Would it be okay to by a used/ refurbished ecm, or have the ecm repaired,and also, how difficult is it to replace myself? I have four oxygen sensors, so should I replace one or more of them first? My car intermittently idles rough, almost stalls, and sometimes loses all but the minimal acceleration.
The car is a Nissan Sentra XE, 1.8 liter, automatic, 2001.
100,000 miles.
Thanks in advance for any advice you give me.  

Answer
Joe,

I have had a string of bad luck with the Bosch oxygen sensors and would remove and diagnose the sensor before I replaced the ECM.  Further, a used ECM is find provided you get one from the same model and year for your car.  But, check the oxygen senosr first.  Also, be sure the converter is not melted.  I have repalced several on the Sentra and the diagnosis was what yours was.  It is a couple of hours to remove the converter but worth the trouble to properly diagnose the car.