1991 Ford Escort idling

First off I don't think the milage is right on this car. I just bought it last weekend. Just for further understanding the vehicle is a Escort GT. When its first started it revs to about 4500 to 5k, then it bounces from 0 to anywhere from 3k to 4k sometimes worse and sometimes better. Once throttle and into 3rd it is smooth, but when you come to a stop the motor will rev between 5k to 6k until you let off of the clutch enough to pull the motor down. I have changed idle control, map sensor, complete throttle body. I found oil in the vacuam hose going to the throttle body. It plugs into the bottom nibble of some kind of electical thing sorry I don't know what its called I'm not a ford person. It vacuums the air to the throttle body. The vacuum line going into the top nipple going to what I think is the AGR valve. It is located on the side of the intake block. The openings in it was caroaded closed I cleaned it out and the hole going into the intake. It still idle roughly though. I think it is sucking air from some where or it the rings or valve guide. What is ya'lls best thought. I think its better if I just overhaul it all.