why does my car idle funny until its warm? It will rev it self from like 1k to 1700, until it gets warm...after it gets warm, its perfectly fine idle at 900. I dont believed I have any vac or boost leaks. I have between 17 and 20 vac...anyone have any details that will help me out with this...im assuming if i needed a fpr it wouldnt only do it cold, but all the time. anyone?