A340h transmission

Hello everyone I'm new on here
I'm also an old fart and not too great with social Media stuff or this little computer I hold in my hand
Anyway I'll get right to it I have a 1995 Toyota 4Runner I bought and fixing up for my granddaughter I've got a transmission issue it has the a348 in it and when it's cold you start it up putting gear drive it it first it was driving good just every once in awhile it would like slip out of gear or something and not wanting to go in gear when you turned it off and put it in dry Park and you know started it back up after it got warmed up didn't do it when it was cold now it's gotten to doing it more regular change the shift solenoids change the transmission fluid twice any ideas any suggestions of what it might be seems to work really well except when it gets hot or gets warmed up?