My car has recently started too idle really high, about 1200 rpm, when in park. It does not happen every time but probably 9 out of 10 times. It drops down too about 750-800 rpm when put in reverse or drive. The IAC reads 0 on the scanmaster and if you give it a little gas it goes up too around 30 and then starts dropping back down until it gets too 0. I have replaced the IAC and the same thing is occuring. What else could be causing this?