Digital gauge or factory? I thought the factory gauge didn't even work and now with 340k km's on the 1kzte and dealing with a few issues within the fuel delivery system the truck is running hot as well. Into the red until the rad was rebuilt a few weeks ago but with temperatures sitting around 40C /104F here in central America plus about 800+LBS in the truck and 33" MT's combined with the mountainous terrain... She's still getting hot. I won't let her get into the red but I can moderate with driving style. I'm using an EGT gauge tapped pre-turbo into the exhaust manifold blanking plate after deleting the EGT and it seems the temps are tough to keep as cool as I'd like in this weather, especially with altitude.
Truth is before the overheating the water temp gauge never moved so a cracked head is likely despite no other symptoms at all, no bubbling, clean oil and coolant, no smoke. I'd say you might have a hairline crack as well. Big thing is your driving style at this point man, if you see she's getting hot just drop O/D off or even throw it into second. It's hard driving so slow but damage control is necessary until you figure it out.
If you don't want to tackle the head yet I would 100% do the standard 1kz safety measures if you have the $$ (I don't).
3" Exhaust - at least downpipe
Intercooler
Manual boost controller - turn it up to 14PSI
Delete EGR (if you can - I know legality is iffy)
Also I would really really recommend some good gauges, I wish I had done that sooner, would have saved me a LOT of headache... These trucks are old and slow you can't just bomb mountains brainlessly in hot weather when they're stock.
