97 check engine lite, O2 sensor

On my tracker , check engine lite stays on with a bad o2 sensor code. I replaced the o2 sensor but the code will not clear. My Mechanic told me that this year had an issue when the o2 goes it takes out the ECM. The engine is running very rich and idle is a little rough. Has anyone had to replace the ECM because of this or heard of this issue. I am trying to find a ECM repair shop now