1999 Kia Sephia idling problem, need to know what hose is o

When I am slowing down or coming to a stop sometimes after car has been running for 20 minutes or so the idle will not slow down and then if I put it in park it will rev very high. Then tryin to put it in gear while reving high is not good! It jerks tranny so hard. Also I need a hose that is blocked off with a screw in it cuz it tis too short to go into back of top left of engine. Its like a vacuum hose. I dont know what piece I need to keep it in the engine. It doesnt have room for a clamp