I have a 01 Elantra with a idle problem,when you start up it goes into a fast idle,as soon as you put it in gear and start driving it's fine.I replaced the throttle position sensor, no luck.I see where someone replaced their coolant temp sensor and that fixed their problem ( didn't seem logical to me) also one person replaced intake air temp sensor ( also doesn't seem right)
any help to pin point this problem---- thanks

You might try cleaning the idle air control valve. My 2002 Elantra had an erratic idle, I took the idle air control valve off, and found that it had some build up in it. I took it off, cleaned it out and sprayed a lilttle lubricant in it, and I have had no idle problems since then. Its right by the throttle position sensor, has 2 bolts and 1 electrical connector on it. The valve should move easily by hand, if it doesn't that might be your problem.

You might try cleaning the idle air control valve. My 2002 Elantra had an erratic idle, I took the idle air control valve off, and found that it had some build up in it. I took it off, cleaned it out and sprayed a lilttle lubricant in it, and I have had no idle problems since then. Its right by the throttle position sensor, has 2 bolts and 1 electrical connector on it. The valve should move easily by hand, if it doesn't that might be your problem.
After playing around with a few of the connectors on a couple of sensors it went back to a normal idle,I don't see anything I did to get it to idle at the right speed.If I have problems with it again i'll take your sugestion and clean that idle air control valve.Your advice sounds good to me.----Thanks----