Your imagining things. No way would this affect the idle. Would not
affect a whine either. Overfill really means over fill by a lot!
My camry has a whine at 68mph since new 220,000 miles ago.
Really not a problem.

Correct transmission fluid level - not as easy as it sounds

The manual calls for checking hot, but not after driving for lon
periods at high speed, or idling with air conditioning on in ho
weather. In these cases wait 30 minutes. Fluid temperature should b
between 158 - 176*F, and level between hot marks on dipstick. That is
not above the "dip" center of the upper mark
Then the manual has a note in bold capital letters: "Do Not Overfill.
I thought I'd been doing this right but I actually had filled slightl
over the top of the top mark. (the part where the "dip" ends
Drove the car for 9 miles one evening and the fluid level was betwee
the  "hot" marks
Then checked it after a longer freeway drive and was above the to
mark
So let it cool awhile, placed an oven thermometer on the case and i
read 165*F, so I siphoned off a bit of fluid to get it just at o
slightly below the "dip" center of the upper mark
Surprise
The car seems to run better now. There was always an unidentifiabl
whine in the transmission which I'd thought was normal - now gone, plu
it seems to idle more smoothly. Perhaps just my imagination, or perhap
they actually have a good reason for saying "do not overfill.
If it took me this much effort (I usually add back in the same amoun
drained by measuring in the graduated empty quart oil containers)
imagine how likely it is that the quick lube place gets it right firs
try
No changing auto transmission fluid won"t give you better idl
if you just did a flush & fill you only got about 40% out i would repeat
another flush & fill after a week and change the filter to  keep i
mind the cleaner the inside of your automatic trans stayes the
more longevity you add to it. and make sure you use O.E.
"original Toyota fluid" that two is very important for its longevit
i see your carefull at not overfilling thats good t
see. overfilling an auto transmission will foam up the fluid causing
airation in the fluid witch is not good for properly lubricating a transmissio

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johnin