If the temp sensor in the rad cuts on the fan, and the fan cools the rad,
that would cause temp fluctuations. I would burp the radiator....get rid of any air inside.....and wire the fan to be constantly on when key is on.
I would have an active fan when the A/C is on, otherwise the
"A/C radiator" will warm up the motor's radiator.....-Bob
Does the power steering have a small tube that acts as a cooler?