It wouldn't be a bad idea to have a look at valve clearances with this mileage (believe Toyota recommends 60K mile intervals; that was the recommendation on my 1993 3.0 and I'm guessing you have the 3.4).

My only concern is that there aren't many techs (in my experience) that have the ability or inclination to do a proper job of it. It is important to be fastidious (even anal-retentive) to do this job right. You could easily wind up spending at least a couple of hundred dollars and having a pickup that doesn't run as well due to incorrect clearances (you realize that these are shim-adjusted valves, right?)

If you are mechanically-inclined and have access to the factory procedure, you should be capable of at least checking the clearances yourself. Basically you need to remove enough stuff (I'm not familiar with the 3.4; I only know it's a 4-valve head rather than a 2-valve) to be able to remove the valve covers, then turn the engine using a breaker bar on the crank pulley so that you can check clearances at certain points along the crank rotation. Toyota specifies a range (say 0.10 to 0.15 mm) for each clearance, so you have some leeway. If clearances are out of spec, you must remove the shim for the valve in question (again, not being familiar with that engine, you either need a special valve depresser tool or must remove the camshaft) and swap it for the shim that provides a clearance within the proper range.

In my experience with shim-type valve adjusters, the engines usually "settle in" after the first adjustment and may not need another adjustment for the life of the engine. But it sounds like this one has never been touched.