Overdrive, transmission issues

[JohnMed]

I have also noticed that if it "cools down" it goes back to normal. What's up with that?!

 

[Patassa]

I'd do full 12 qt flush with Mobil 1 ATF in 98-02 100 series. If 03 Toy IV, if 04- up Toy WS ATF.
But first, I'd also monitor engine coolant temp and AT temp. Than again after full 12qt flush.

Can the Mobile 1 ATF be mixed with the toyota AT fluid if I want to do partial drain/refill over time?