I believe that your problem is a bit simpler than that, if your problem is hot revolutions, you have to check first of your IAC valve first, after realizing a cleansing of it, you see whether it improves or not, if it does not improve then with the auto in working temperature I suffer a little the revolution from the pedal adjustment screw, since the normal thing is normal for that vehicle is between 850 RPM, at working temperature, it is normal for these revolutions to be between 1500 and 1700 rpm, é mais em Toyota Yaris, ligue para 2000 rpm e cai progressivamente na função da temperatura, pois as revoluções são tão baixas em alívio tendem a interromper o motor.