2005 tacoma 4wd with auto od shifts too much

I have a 2005 tacoma 4wd, 6 cyl and 5 speed auto trans with od. The trans seems to be erratic and goes into od at low speeds, usually under 25-30 mph then will downshift. I have 43000 miles on it and was thinking of getting the trans fluid and filter flushed and changed.Now I hear that its a sealed trans and uses a special Toyota fluid. anyone else had this problem?

 

Weird maybe drain the oil and replace it but idk maybe someone else will chime in

 

thanks wolfpack, seems kinda strange the way the trans shifts up and down in od. i drove around for a few days in 4th and it seemed ok. the manual calls for a fluid change at 30000. also I read somewhere that theres a fuse that resets everything. thanks