high idle

[adamh88]

So the other day I was leaving to a friend's house and I started my car and as always it idles crappy for a few seconds. So I rev it a little to get the idle up so i can go and oh it went up to about 2500 rpm and would not come down so i pop my hood and check for stuck linkage or anything like that and nothing. So I turned it off and the right back on and it was fine. It lasted aout 2 days and then started doing the same thing. so today I checked out my vacuum lines and replaced a few and fixed another and it still did the same thing. So i got irritated at it and floored it while i was starting and it idles fine so to test it i turned it off and started normally again and it was back high. I did the same thing and it seems to work fine if its floored when i start it (which i know isnt good for it) anyone know what this might be and how to fix it??? please help