I would say a good look at all the suspension bushings, shocks, and brakes. Greasing the u-joints in the driveshafts. Toyota recommends 30k mile spark plug replacement, so I would do that too. I would also inspect the fan belt. If its never been replaced its probably due. Flush all fluids, transmission, x-fer case, front and rear diffs, power steering, and don't forget about the coolant(anti-freeze).
I guess it would depend on how much longer does your sister intend on keeping the 4runner. Is it her daily driver? Thats a lot of miles, are most of them highway?
__We got the shocks replace with OEM at 115K.
__Hope the local Toyota dealer is lubing the u-joints with the oil changes.
__I thought the sparks plugs were 100K plugs. Opps, I learned that they
were supposed to be change every 30k. Sparks plugs changed at 115k and
160K. I'm going to change them next week at 191K.
__ Fan belt is the original OEM. I'll check it next during tuneup.
__ Fluid Flush. All fluid are original OEM fluid that we never change as I far
as we know. So, that is the next maintenance to do. I just need to look for
a how-to writeup on T4R forum.
__ Antifreeze is the original OEM since new, so that will be address also.
__ Engine is a V6 so no timing belt, but I need to look at the waterpump also.
__ I was wondering about Seafoam to see if it was worth the effort at 191K.
She plans to keep it; it's her daily driver with mostly highway miles. I just need to polish the headlights also.