You sound like an “unhandy” type of guy. You’d be better served to buy a new car with a warranty. If you start the typical maintenance needed on 125,000 mile 4runner and will be paying a service shop for the work, its going to get expensive quick and will likely cost more than the truck is worth.

When I bought my ‘07 sport with 222,000 miles, I spent another $1,000 in parts alone to catch up the maintenance. But I did all my own labor.

Quick update. I went and actually test drove a 5th Gen 4Runner for the first time today. I was surprised that I actually didn't like it. I felt like it had less visibility out the windshield and less acceleration. I didn't like the center console setup and I noticed it was missing even little things like Auto on the HVAC. I did like the 120V outlet in the rear, but felt like this was one of the only upgrades I'd actually appreciate.

I think I'll be sticking with my 4th Gen for now, and evaluating a Tundra in a year or two when it's a bit more seasoned.

That's a sound decision. With the Tundra, you're not going to be happy with the gas mileage. 20 mpg on a V6 4Runner is going to look pretty good once you get into a bigger heavier vehicle like the Tundra.

Of course that's going to be offset with the money you won't spend on this 4Runner's maintenance.

It's a question of: do you need the capabilities of the 4Runner? Or for that matter, the Tundra? There are lots of good mid-sized trucks you can buy new right now that might be options to think about.

I need my 4Runner for its capabilities, so I'll put up with the mpg and maintenance. There's nothing like a body on frame SUV for bad roads and bad weather.

I didn't take time to read all the replies but... in my opinion you would likely have more problems with a new model domestic vehicle than you will with your 15 yo 4runner. The only difference is that the new vehicle would presumably be under warranty. And there's virtually no way any repairs you might face on the 4runner would ever equal what you would be paying for a new vehicle. But, if you're like I have been at times and you just want something new, you might not be happy until you get it.
My 05 V6 has 341K miles on it and it still runs and drives perfectly. I've only had it about 3 years but about 75% or more of the money I've spent on it has been for mods/upgrades. (Wheels, tires, lift, stereo, etc.) Good luck whichever way you decide.