This morning I took my lil girl to school and the engine was reving real high the entire drive until I got back to the house. On the drive home I tried goosing the gas peddle trying to unstick whatever is stuck. (I had to do the same thing in my 84' Jimmy and it would bring the revs back down) Well it didn't work. When I got home I put it into neutral and nothing. Still high revs, but as soon as I put it back into park. The idle came down to normal. I put into gear and nothing. Stayed good. Any ideas? First time it's done this. Did I not wait for it to come down to normal idle before I put it in gear?

 

TB is dirty or the IAC is dirty or the IAC is loose from the TB. All of thse will cause high/low idle problems. Check those and post up if that cures it.