[highlandlake]

If your problem gets temporarily better when the check engine light comes on, then it could be that the ECM is switching to a default setting mode when an error code is triggered. I don't know enough to suggest which sensor is causing the problem, but thought I'd share this info if it helps narrow down the possibilities. Some sensors such as the Throttle Position sensor will be overridden when in default mode to allow the vehicle to be driven safely for a short time. So maybe the O2 sensors will do the same as suggested above. Let us know what the outcome is.