How do I lower engine idle speed,or what part needs replacing? Rpm is 1500 on 1992 Subaru Loyale

Car is 4wd wagon, 1.8 TBI engine, it revs very low when first started then idles very high after it warms up, 1500 rpm, normal is about 700.

Asked by for the 1992 Subaru Loyale
Check for vacuum leak.
Thanks for your reply. I have checked for that using a can of starting fluid and spraying around vacuum lines to no avail. But, I will try again as that has been suggested a couple times. I live in a remote area with no mechanics that can deal with this so I'm groping in the dark. I thought of unplugging certain components when its running to see if that shows me the component problem.
Try cleaning throttle body and idle air control with carb. cleaner.