Why does my car idle high when I start it up then idles low and high.

What is your question?

My chrysler aspen 2007 idles high when I start it up now matter when it is then when it idles down it seems like its idling low to normal almost like its going to cut off. I got it diagnosted but they say it might be a wire or sensor they don't really know but I can get an overall inspection for 180.00 dollars. Can anyone help?