88 toyota van 2wd automatic shifting

I bought an 88 automatic 2wd with 116k miles on it a couple of months ago. I noticed that i had to "manually" shift gears by letting off the gas pedal. 1st gear shifts automatically into 2nd, but from 2nd to 3rd i have to rev it up to about 25mph, let off on the gas pedal, and it shifts. from 3rd to 4th it shifts at about 32mph. My tranny isnt slipping and it seems to be shifting fine, i was just curious to see if anyone else experiences this? My van was ordered directly from the factory in Japan (said the previous owner) whether that means anything or not.

Thank you!