It's been a while since I participated in this forum and I want to add my experience with my brake system on my 2004 4 Runner.

At 30,800 miles, both front calipers were sticking and were replaced by a Toyota dealer.
At 44,225 miles, both rear rotors were replaced by an independent dealer.
At 64,375 miles, both front calipers were seized up and replaced along with the rotors by a Toyota dealer.

So it appears to me that there is a defect in the design of the calipers.
I always start out slowly to be begin my acceleration and I brake the same way.
This is the way I have always driven my cars or suv's.
And I thought one could not go wrong by buying a Toyota.

There is absolutely and always has been a serious design defect in the calipers for this generation.

If you have worked closely with Japanese before, you will understand why they do not address the issue - The same reason they haven't addressed the frame rust issues on this generation. They designed it and built it or directly supervised the build. The Tacoma frames made by Dana could be blamed on Dana without losing face. Admitting the problems with this generation (and with the calipers, and other well known issues) means losing face and this is very difficult because of how their culture works. They will eventually concede but it takes a long time and lots of formal fighting.

4 4runners of this generation in the family and we have probably replaced 20 front calipers between them over the past 10 years or so. Some under warranty and some not.

Coincidentally, this is also why Japanese are so resistant to change in their designs. Very cautious, they analyze everything to the n-th degree before stepping forward so that things like this don't happen. Very fascinating side of the automotive industry. Basically the opposite of FiatChrysler (What? It came out yesterday? Nobody knows if it works? PUT IT IN ALL TEH NEW CARS NOW I WANT IT ON THE DEALER LOT NEXT WEEK WHO CARES IF IT KILLS PEOPLE WE CAN LET THE LAWYERS HANDLE THAT)

Replace the calipers with good warrantied units and keep the paperwork if you keep the vehicle - You WILL need it.

Thanks,
I have the receipts for all the repairs since I bought the vehicle. On my next visit for maintenance, I will ask the service manager if there is a warranty or guarantee on the repair of my brake system. It cost me a bit over $900.00 for the calipers, rotors and pads.

i bought a 2007 sport in late 2016 that had been in Ohio all its life. I moved it to Arizona after purchasing it and both front calipers froze about 3 months later. I used remanufactured A-1 Cardone (both cheap, like $45 each), which was an easy install (maybe 30 min? although I recall bleeding them being a PITA). No issues since, now almost 24 months and 10k miles later.

not sure how/if weather/moisture plays a role in this. i recently located to the NE; will keep an eye on them.

if this is a defect with the design, at least it's a problem that can be rather easily and cheaply fixed.

How does your frame look? Mine (with all the holes in it) is also from original Ohio owner. Near Toledo. I believe they drove regular winter trips up to Michigan so it probably saw more salt than the average Ohip T4R, however he washed it religiously (even gave receipts for this) and the body is in flawless shape, not a spot of rust - Only frame and axles/control arms are rusty. Even underneath the body is spotless.