2000 V70 Strange Cooling Issues

[s10lowrider1994]

Here I sit again, stumped about my v70 and its random cooling issues. A few weeks back I had a problem with the fans not working and occasional hard starts. Replaced the ETC sensor and thermostat, hard starts went away and fans started working again, figured I had whipped it.

Well now I have two more odd problems that I'm lost on, I have a live data scanner so I've tried to pinpoint the issue but haven't had any luck. Here's what it does, and doesn't do:

In motion or at idle, the car will not get above 147 degrees with the a/c or defrost on. I'm assuming this is because of the high speed fan being on, and the thermostat being stuck in the open position. Now here's where it gets odd. With the a/c and defrost off (IE so the high speed fan doesn't run), the car will slowly creep up in temp at idle until it overheats, literally coolant boiling in the reservoir, but the gauge sits at 3 o'clock and the scanner only reads 187 degrees. How can an engine that is 187 degrees boil coolant? Why would it go to such different extremes of hot and cold? I'm thinking that not only is the thermostat stuck, but the new ETC sensor is faulty. It's reading 187, the low speed fan is never kicking on, but the coolant is boiling. Of course when this happens I can turn on the AC and the temp drops rapidly back to 147. What gives?

[abscate]

Scan the threads for the table of ECT resistance vs temperature, I think mike (precopster) posted it recently. That will confirm the ECT function