Toyota Repair: Low Idle problem, 2009 toyota corolla, throttle position sensor

Question
2009 Toyota corolla 1.8 5 spd.  Cleaned throttle body, changed plugs and gapped .44 cleaned all connectors that connect to plugs, cleaned MAF sensor with crc maf cleaner. Used dura lube injector cleaner, all ready fill tank done.  My car still idles at 600=650 at times and car shakes.  This is when it is fully warmed up. When cold idles high but no shakes, only when its warm, but fluctuates upto 800-900, for about 2-3 sec, then down to 600-650 rpm for about 4 seconds then back up again.  Then when I turn on the rear defogger, rpms go way down and shakes real bad, goes back to 650 rpm and repeats.  Even when I have the fan turn on high or turn on high beams, it just shakes and rpms drop at least to 600rpms.  Come to a sudden stop and does the same. I have not changed or cleaned the iac but not wanting to do, cause its a big jkob i assume.  This is really pissing me off, please help me out here, thanks Ted.

Answer
Hello, it doesn't have an IAC valvbe the idle speed i s controlled by the computer via the throttle position sensor and the throttle motor. Do you have a check engine light staying on, there have been some cases where the throttle body has to be replaced to cure this problem.