I have a forte ex m/t. My car just started doing this or i'm just now noticing (Had it since june 12)...In the mornings or when it has been sitting for awhile the rpm goes to 1000 like normal but after a few seconds it revs up all the way to 3500. After a few second it then gradually goes back to idle at 1000. Following that there is this small rattling noise. I'm not too knowledgeable when it comes to technical issue with my car yet. Just now getting really into them so if this is a stupid question sorry lol...so is this normal? I was thinking it does that to warm up or something. I'm really not too sure.