'89 Supreme running rough after changing O2 sensor

In response to code 44 and 45 (Exaust rich and Exaust lean), I changed the O2 sensor on my '89 Supreme, 2.8 L.

While the sensor works correctly now, verified on the scanner as it was never making it past the closed loop state, the car is running badly. Fluctuating idle, 'stuttering' while accelerating, almost feels like a fuel delivery problem. My understanding is that the O2 sensor is working, the engine is no longer operating off of table values in memory but trying to figure out the mixture, etc. on its own. So I'm guessing the Baro sensor (or some other one) may be messing up. Baro is supposed to operating at between 3.0 and 4.5 V but is operating at 4.78, which might (?) be enough to mess things up.

I finally got a Service Engine light so I'm going to look for codes again but was wondering if anyone had ideas. It's possible we could've 'bonked' something when moving the block forward to do the sensor.

p.

I used to have a 90 Cut Supreme with a 3.1L. I had to replace the O2 sensor as well. Try disconnecting the battery for 15 minutes then, after reconnecting it, let the car idle for about 5 minutes. This will reset the emissions control and may help your problem.

Thanks. We have done this, after struggling through one bad 02 sensor, and our problems have gotten worse. :( Now, the 02 sensor is behaving correctly but we are still getting 44 and 45 and the engine is running very rough, especially on acceleration. Much stuttering and hesitation, feels like fuel delivery but we're still looking...

had same problem got ecm from wrecker put my eeprom into it ... all faults gone car runs perfectly again. mine was behind glove box, need to get all numbers so it can be matched properly.(cost$50 canadian)