What is your skill level? If low then either you need to study up on the system or get some professional help. I would approach it this way: For the engine to run, air has to go in it. If idleing high then too much air is going in it. For 2000 RPM that is a good amount of extra air. You need to know all the ways air can go in. I don't know that engine/EFI system but generally there is: The throttle, the idle control valve, some emmissions lines such as gas vapors and PCV and EGR, that all lead into the throttle body, and some vacuum lines of course.

You need to try to plug up each of these one by one to see if it is the culprit. For example, you can see if there is a way to make sure the ICV is closed or just plug up the passage way if possible (again I have no knowledge of that engine). Then if it still idles high you can then eliminate the idle control system. If it doesn't idle high then you have found the trouble.

Yes there could be a vacuum leak. I think some times people spray Gumout around to see if the idle is affected. The idea being if it gets sucked in a hole then the idle will change.

__________________
1998 C230 330,000 miles (currently dead of second failed EIS, yours will fail too, turning you into the dealer's personal human cash machine)
1988 F150 144,000 miles (leaks all the colors of the rainbow)
Previous stars: 1981 Brava 210,000 miles, 1978 128 150,000 miles, 1977 B200 Van 175,000 miles, 1972 Vega (great, if rusty, car), 1972 Celica, 1986.5 Supra