Step 1, make sure the engine is set up, timing, etc. Then make sure your gearing is close to factory, oversized tires will kill it, if you dont change your differentials, specially if your engine is over 100k miles. You should get some relief. Stock size tires dont' look as cool... but...
footnote, this is not a T100 think, it happens to any vehicle as it gets tired...

98 Taco 4WD