Rpm fluctuations in these toyota models,main issue could be in electric wiring short,check the maf sensor all 5 wires and rheir metal clips inserted in main maf sensor plug,As with passage of time these copper wires and clips get dirty and gunki,clean them,mainly this issue of low idling arises when current is leaking,if any wire of sensors,like iac valve or tps or maf sensor are jointed and taped,open that old taped wire and cut older copper exposed wire and peal new copper wire and again tape it, do this work by reputable elecrician.
I have also faced this problem tried everything,but useless,the culprit was maf sensor 2 wires,i have repeated above said procedure,then problem was solved.
