[s-cars] wonky temp guage

[ron kirkham]

Fellas,

Over the last several weeks my temp guage has been acting very weird.  Car
will be fully warmed, and guage will read barely off the low end.  Then, it
will go up to the normal hash mark where it's supposed to be.  Sometimes
this will happen two or three times in the course of my 45 minute commute.
Sometimes it doesn't do it at all and will read fully normal.

Victim is a 93 S4 with 221k.  T-belt and t-stat were done at 215k and all
seemed normal until a few weeks ago.  No gas mileage change.  No performance
change.  Coolant level is where it's supposed to be, and I'm fairly sure
there are no bubbles in the system.

Bad t-stat?  Bad temp sensor?  Other thoughts?

Thanks all,

Ron
93 S4