I have no real temp gauge in my truck yet (got one in the 4runner)
some quick history, back in 2001? the second HG blew on my 3vze. At the time i had to have my truck for a reliable DD so i bit the bullet and had a Jasper dropped in. Its bored .30 over as part of there rebuild. For the year before the HG blew the temp ran dead nuts center gauge, never moved.... The 4runner the temp guage runs dead nuts center no matter what (dispite 40 deg changes in the real temp gauge i have plumbed in)
Ever sence the Jasper install its run about a full needles past center ONLY on the interstate.
I can sit at idle all day long or crawling along a trail with the AC blasting away and never break the middle of the gauge. Jump on the intersate and try doing 75 and i start riseing quickly.
If i turn the heat on full i can manage to get it to drop back to "normal" but recently it seems to be getting worse.
Popular thought is fan clutch is dieing a slow death..... you concer?