V70, petrol -00. 200'000 km

I get ETS error lamp almost daily.
Never during the first 5-10 km, but after this, when it's warm, it happens.
ETS lamp goes on, and the car looses power and has terrible idle.
I also have an ODB2 terminal. Error code 1603 or 1610, about 50/50 chance.
I acknowledge this and the car runs for another day or two.
Okay, you say, "It's the throttle house. Needs cleaning or replacement."
I have the older model , some call it "the white sticker, not the yellow"
(and I assume it's probably the position sensor (potentiometer) that is worn out in my throttle house)

I am okay with this.... BUT :

If I use the "Cruise Control" basically all the time when I drive, I NEVER (!!) get the ETS lamp or any malfunction (in power or idle).
Wouldn't I get the error even here, if the position sensor inside the throttle house was bad???

So... this is my dilemma... A new throttle house is very expensive.... so I want to be sure of this...
Couldn't my problem be the gas pedal sensor? Or something I don't think of?

VERY grateful for your thoughts!!
/Richard