Toyota Repair: rough idle, throttle position sensor, 4wd auto

Question
why does my idle drop when in drivewith foot on brake to the point that the engine starts to vibrate ? i have a 2003 tacoma 4wd auto 2.7l it wil drop down about 200 rpms then come back up. sometimes if you turn the wheel or shift it to nuetral it comes back up. it only has 44,000 miles on it. i did spray throttle body cleaner in it but only lasted a couple of days before it started again.could it be the throttle position sensor is shot? thanks scott

Answer
The TPS malfunction would turn on the check engine light so that's not it, you took a step in the right direction but did not go far enough, the problem is the idle speed control valve, remove the throttle body completely and then remove the ISC valve from the T/Body and clean it with the cleaner to remove all the carbon deposits,also clean the inside of the T/Body again using a small brush and the cleaner, put it all back together and the problem should be gone.