weird revs?

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hey! it's been a while, but the yaris sedan and echo coupe have been doing well - until now that is...

my echo started having issues with the rpms at idle. i can't tell you how many it goes to(no rpm guage), but it gets pretty high. i don't have issues when i'm in gear(it's a manual), but anytime i'm in neutral i get higher revs. first, i cleaned the throttle body and the 'butterfly flapper valves'. i used standard carb cleaner as recommended by the auto parts store guy and it didn't really help - it was fun to work on the car, however.

went to the actual toyota dealership and $500 later and many trips back and forth it revs a little lower. they say they cleaned the idle control valve and cleaned everything else i already cleaned, but i'm still not sure it's much better. i really think they just wanted to get rid of me and my 15 year old car after numerous attempts to inspect/repair it.

anyways, they mentioned something about it possibly being the ecu after they pretty-much threw their hands up in the air, but that is costly for something even they couldn't guarantee would help($800ish). i did notice, however, the other day when i turn on the defroster it makes the idle rev higher than normal. it's weird, i can be sitting at a light or just warming up the car and when i switch the fan to 'defrost' it starts reving even higher and then lowers to it's regular higher-than-normal speed once i turn it back to normal.

any ideas? thanks and it's nice to still see some old names on here!!!!