I bet If I was a professional mechanic, I would have to invest in some hardware and software for sure!
OP, can you elaborate on this statement?
"...the ECT jumped up to 82 and then 85. It would fluctuate up and down..."
The ECT rising that you described recently sounds fairly normal, but a significant "fluctuation" would not be.
When I pulled up the live data, the ECT was more erratic.
the next time I started cold and took readings every minute, it progressively went higher compared to the IAT.
just got home from work and IAT was 48 and ECT was 52.
MAP started out at 29 and dropped to 11 until it started and it stayed there.
now after running for about 3 minutes, ECT is 113 and IAT is 52.