I have a 2001 Grand Prix GT-3.8 and i have a problem with the idle. When i start my car it idles between 2000 to 3000 rpms and then back down..and sounds like it wants to die out..unless i give it some gas or put it in drive( and idle stays normal) I've put a brand new TPS sensor on, i've cleaned the MAF sensor and dnt kno what else to do or what could be causing this..Plz Help!!!