Okay, I just replaced 5 qts of Elsies transmission fluid (Walmart Supertech Dex III) with Toyota OEM T-IV.
What a difference. Smoother, better timed shifts with just a drain and fill. Plan on replacing the rest in the next few weeks.
Lesson: IMHO in this case USE TOYOTA T-IV AND NOT...
My engine (1FZ-FE) cuts out or has a very low idle <200rpm after:
-it comes off the freeway or a long high speed drive
-I come down a hill to a stop
all this of course after it warms up.
Curiously, after it dies and I restart the engine it runs smooth, idles normal @ 600rpm.