Toyota Repair: 1999 Toyota Corolla LE Idle Circuit, toyota corolla, carbon deposits

Question
Corolla has been very reliable vehicle, however; recently at cold start engine runs rough with speed rapidly changing high (1200 rpm) and low (1000 rpm) and very rough.  I have changed spark plugs and air filter and that has made the engine run little smoother, but it is not running normally which is steady idle speed and very smooth idle.  I appreciate any suggestions to correct the problem.  Thanak you.

Answer
Try cleaning the inside of the throttle body, carbon deposits in the throttle body can cause these kinds of unsteady idle problems, use a can of spray intake cleaner and a brush and clean all the deposits out, disconnect the battery before doing this after that drive it for about 20 minutes usually this restores the idle to normal.