Unnecessary (& rough) running ICE

In the last two months my car has developed an ICE idle that is both rough and occurring when unwarranted.
As we are used to, the ICE will start when the battery is low or when the throttle is depressed () enough or when speeds are high enough to warrant it. When it does so, it's still a smooth running engine and it kicks off as the software & conditions dictate. That's been well and good for over 285,000 miles and nearly 8 years.

But now, a third condition has appeared, a rough "idle" that can actually be felt through the steering wheel & armrest as well as heard. It occurs intermittently, mostly at times when the ICE should be off (though occasionally when it is already running) such as when decelerating (approaching a red light/stop sign, foot off the throttle and more than 2 bars showing on the battery indicator) or when sitting at a complete stop where it sometimes kicks in and runs for several seconds (up to 30), again with a half full or more battery indicator. On more than one occasion it actually revved higher while at a complete stop or slowing towards one.

There appears to be no commonality here other than it should not be running in those conditions nor has it ever been rough.
Any thoughts, folks?

 

I am approaching time to replace plugs. Hopefully, coils not needed. Fuel cleaner is on my list and hasn't been used in months, unusual for me. I'm putting nearly 1,000 miles/week on and haven't cleaned the tank yet this year.
It kind of feels like a odd sensor thing since it is so random. Most of the time the ICE runs smoothly as it always has but then this roughness overlays it occasionally under the weirdest situations.
ATF has not been touched as it is sealed for life at the factory. I'm also nearing periodic maintenance on several areas, flushing the engine coolant & hybrid battery coolant among them. If plugs & cleaner don't do anything, I'll inquire at the dealership when I ask about PM @ 300k.

Wait until I tell you how long the brakes lasted

 

Stopped by one of the local dealerships yesterday. The info I got is NOT making me happy
According to Golling Toyota in Warren, MI, the engine coolant, inverter coolant, and front differential fluid are all supposed to be replaced every 30,000 miles! And each service costs $270.
My dealer in Bradenton, FL, told me 100,000 miles on coolant and that the tranny was sealed and was good for life.
One of these is definitely off.
A phone call to FL is going to be made. If they are wrong, all hell is going to rain down on them. If the local place is wrong, I will be doing a Karen impression there with the highest up the food chain person I can find. And then go somewhere else.

 

I actually read that entire 800 page manual - except the 15 pages in French - when I bought the car and have referenced it numerous times since. Haven't found it yet since the move, though (Oct. '23)

Gotta love how the first item is to check the driver's floor mat. And third is check the wiper blades.
And replacing the oil & filter, plus tire rotation & inspecting the air intake filter for the hybrid battery, is specified for every 5k miles in mine (I suspect you left those pages out)
I replace plugs more often, about 80-100k.
Had the engine & hybrid fluid replaced somewhere nearing 150k, if I recall correctly. Will attempt to confirm when I call FL dealer.

I definitely appreciate the info, RJ. I'm going looking for that manual again. Going to beat the service tech with it. Maybe.

 

Oh, you ain't kidding there, boyo! And it isn't just the dealerships, many of those chain repair places will do it too. I once saw an older guy, in his 70s, pay almost $70 to have his windshield wipers replaced when he came in to pick up his car after being serviced. $17.95 per wiper and $29.95 for putting them on, plus tax, of course. But they threw out the old ones for nothing. I buy mine online, about $3.50 each, average for all three. Takes about 30 seconds to do. Ringling was right, a sucker born every minute.
Just another in a long list of reasons to be an informed person, whether it's car repair or voting or buying a house, do your due diligence or suffer for your stupidity.

 

I contacted the service people in FL. I was told that, after 2014, CVTs are sealed at the factory and do not require any normal maintenance.
I do not have that in writing, however. I still have not found the manual, because I haven't had time to look. Tomorrow morning/afternoon is pretty wide open and now I have a second item to find.

Update: The "rough idle" has decreased in occurrence and duration but is still present. I've run three tanks of fuel system cleaner through it since the OP. BTW: It is not like a cylinder has dropped, not a dead/misfiring spark plug, more like something is slightly out of balance when it happens. Sorry if I was unclear previously. It also is not increasing the rpm anymore when it occurs. I am beginning to suspect a dirty sensor or some similar thing.

 

A wee bit of a follow-up.
The unnecessary revving almost always is before the engine warms fully.
On the 300k mile PM work, I have spoken to more people and another dealership (Matick) and gotten some other useful info, I feel.

The transmission. It is sealed and cannot have the level checked but it can and should be serviced every 100k (Yikes!)
The hybrid battery/inverter coolant & engine coolant are due at 100k, not 150k (we knew that)
The non-functioning TPMS sensor has to be replaced but is powered by battery. $170 each. Not going to bother, I know how to use a tire pressure gage and expect the other 3 will follow soon enough.
The work at the 2nd dealership (we have 8 in Metro Detroit) is significantly less expensive than the 1st one referenced (Golling). The coolants are $80 less each ($190 vs $270). The tranny is $310 vs $500. It pays to shop around, 2nd opinions are great. The estimate from 2nd dealer is under $700, the 1st was over $1850.
Going to make an appointment for the end of the month.