I should have jumped on this. I suspect my STI thermostate is sticking...
needle stays in the wavy lines most of the day. then out of no where, even under cruise control it goes way up. way above the normal range. if i turn on the heat full blast it stops going up and comes down very slowly, eventually (i suspect) the thermostat opens up and the temps drop very quickly back to normal. usually a few minutes after that the temps go below normal (just a touch) (even climbing spooner+ AC blasting)
day late & a dollar short