95 celica st shifting weird...

[kandyman282]

Hey guys im new to this forum... just bought a 95 celica st with 150k miles on it, it runs great gets 28-33.5 mpg : )... but every once in awhile it will kickdown into a lower gear real fast... it has the 1.8 with an auto tranny... for example when acclerating it will shift from 3rd to 2nd a few times or when holding it steady at 50mph it will shift to 3rd or 2nd for no reason only for a few secs... this rarly happens but it is still a problem anyone have any ideas? some people i have talked to think it might be the TPS (Throttle Position Sensor)... thank you for your help!