Sounds like Yota geared it a tad to high i fit constantly shifts up and down even in windy conditions. Might check around see what aftermarket rear gears you could put in it, lower the gears it would help just don't go to far or the rpm's on the highway will be high. My 94 chevy think has 3.73 running 70 it turns about 2500 rpms gets decent mileage.
Maybe because I got the tow package with a class IV receiver hitch, but my gears are 4:30. Unless I manually shift it, it stays in high gear and never down shifts even when driving into gale winds.Quite a bit of info about this on some the Tacoma forums. I had one from Dec to March of last year. Got tired of this, 0-60 in about an hour, and poor gas mileage.
What engine were you running Pstmster? My 381 hp 5.7 liter 4 WD certainly hits 60 mph pretty danged quick.