Just out of curiousity, is your HVAC turned on at all when this is happening? The switch on my `96 is trashed. When the fan is on any of the settings, the car looks like it will overheat. When you turn the fan off, the temp drops. I think it is probably related to the heater switch that hasn't had its recall.
I have had it go as far as shutting off all of my guages and dash lights.
Don't know how or why, but it did it.
