hanging idle

Hi, I am having trouble with my idle on my car. It seems to only do it when it warms up. when I am driving it and gets at normal running temp and give it gas it doesn't like to idle down and hangs up high. If im at a stoplight it will just start revving up to almost 3000 RPMS. I replaced the TPS sensor because i thought that was it but it is still doing it. and also today it seems weird but i had the hood open with the engine running and when i shut the hood the RPMS revved a little bit. I was just wondering if you could help me diagnose the problem. THANK YOU VERY MUCH!