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