kind of a bad idle. idle confusion

I have a '90 xj. it idles around about 1200-1500 rpms after a drive when you put it in park. I also tried putting it in neutral, and the same problem exsists.

I have done some research about this problem and some people complain about shift problems. My tranny shifts fine.

People also talk about two sensors. the TPS ( i know what that is) and the IAC. Whats the IAC and where is it located??

Also some more things point out is that the rubber hose from the vacuum canister to the supply line (3/8"-1/2") is pretty dry rotted an its taped on there seccurly until i make a run the the jeep dealer. (thought i could get one from the local parts store, guess not.

Something else to point out is that I just did a motor swap about a month and a half ago. 4.0 to 4.0


Does any one have any ideas about what it could be or what test proceddures i could use to eliminate some things.

everything is apprectated. Thanks!!!!!!!

http://www.naxja.org/forum/showthread.php?t=905849
this thread is pretty useful on all kinds of high-idle problems, there are many, many pages of suggestions that will probably help you out. In the meantime, the IAC is located to the left of the TPS sensor on the throttle body (looking head-on). remove it and try cleaning the recess of the TB and end pintle on the IAC with carb cleaner and see if it helps, you might have carbon buildup on there not allowing it to close or open properly. The IAC stands for "idle air control" from what I remember. It might be a good idea to remove the TPS while your doing this as they can be pretty sensitive to cleaners/moisture. Finally, reset your TPS back to factory specs using a digital volt-meter and see what happens. If that doesn't do it, then consult the thread I linked to you and you'll eventually get it.

For a high idle, always suspect a vacuum leak of some sort. There are tons of potential areas for those... Use a light mist spray of water around all hoses and components; if when spraying in a certain area, it changes idle speed/quality, you know what to concentrate on.

Other thing to consider is cleaning the IAC; I've enclosed a procedure if you're so inclined....Good Luck!
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Cleaning the IAC:
1. Remove the IAC with a torx 15 driver (2 bolts)
2. Gently wiggle out the IAC from the throttle body
3. Clean the IAC with throttle body cleaner (not carburetor cleaner ) Use cleaner, a rag and a toothbrush and or Q-Tips. Be gentle; don’t twist or pull on the pintle as it is fragile and you can damage it pretty easily
4. Also clean where the IAC seats in the throttle body with the same throttle body cleaner
5. Consider cleaning the entire throttle body itself as long as you’re at it
6. Reinstall IAC and check idle quality