I've been reading a lot on the forum about the problems and solutions on trannys here but I'm still stumped. I had mine rebuilt 45 k ago and found out they upgraded the torque converter and a stock rebuild. Had problems after 10k miles with shifting out of gear. Took it to a different shop they did a valve body, shift kit and replaced the tv cable. Thats been 20k miles ago. Just pulled my 14k toyhauler 500 miles lost a tranny cooler line, immediately pulled over fixed it, topped off fluid ( I thought) and came home. Pulled great. Next day it I noticed it shifts into second then shifts back out momentarily. Took it to the shop he checked the fluid in neutral ( I checked in park) so I was two quarts low. He put two in we test drove and was perfect. I gave him 5 bucks and left. Worked great for 1/2 an hour and does it again now. Still lots of power and firm shifts just searches from first to second at low speeds. Checked the band it has lots of threads showing and was in spec. I'm thinking tv cable again?

 

check the govenor position solenoid, or just replace it they go for about 45$ could also be a dirty filter or bands out of adjustment. i had similiar issues with mine when I had it (just sold it)

 

I had the same problem with my 99 and it was the TV cable.

 

Sounds like the cable.
Governor Pressure Solenoid problem will usually be when it does not up shift without backing off throttle.... or if it does not down shift to first at a full stop.

RJ