Thank your for that information. I am researching all avenues. I took it to a local Volvo Specialist that is super good and he said that he had never seen anything like it. After a few hundred dollars in diagnosing he said he couldn't find out the issue. The low speed fan would not engage but he could turn it on with his OBDII computer. I recently replaced the Relay. He suggested to replace the Thermostat and temp sensor which I did with Volvo parts. Same thing after it warmed up. Just changed the oil too. He said the ECM would have to be sent off and rebuilt if the other 2 parts didn't clear it which is nearly a grand. I don't think that's the issue and a really expensive hunch. He cleaned the ECM terminals and looked inside which looked visually good. A broken cable on the link you sent looks to be a plausible possibility. O2 sensor is another suspect.

I was having charging issues about 4 months ago and I replaced the Alternator, which solved the dying battery issue. I wonder if there is an issue there. I'll unplug the alternator while it's running to see if there's a change in running pattern.