ACDelco O2 Sensor made the difference!

After foolishly installing a Bosch "universal" 02 sensor in my 01' Alero with a 3.4L, I still kept getting the same P0135 code. After weeks of playing around, the problem go worse with my Rpms now fluctuating. I reinstalled the 02 sensor, and rescanned the computer to find other issues and found a new code which indicated "low voltage at the 02 sensor." The whole time I regretted not taking BNaylor's advice of going with a Delco unit in this first place. I was dreading taking it in to a shop and having him tell me that it's just the 02 sensor. :banghead:
So, I finally bought the ACDelco 02 sensor from my dealer. I disconnected the battery during the install. I let the car sit for an hour then reconnected the battery. I plugged in the scan tool and it said "PASS - NO CODES." Upon starting the engine I immediately noticed the Rpms had smoothed out and after several days of driving, it seems that did the trick. Knock on wood.