some hints from www.toyota-workshops.de

[NoHachi]

Sure:
1. If the tranny starts to go and shifting becomes more difficult, exchange gearbox oil with ATF (auto-tranny fluid).
2. Exchange bushings with poly or TRD bushings throughout the car.
3. Checking the TVIS activation switch..(vacuum switch): start car to build up vacuum and switch off. Look at switch with help of a mirror. Have a helper put the ignitionswitch to ON (do not start). If al is well, the little lever on the switch should move and you should also hear a slight sound. Otherwise check connections for corrosion.