1995 Geo Tracker high idle during warm weather

Engine Performance problem
1995 Geo Tracker 4 cyl Two Wheel Drive Manual

Hi,
Its summer once again and my tracker which ussually operates flawlessly has began it high idle highjinx during warm weather. It did this last year as well. After much aggrevation and changing one part after another from a doner car, the problem was resolved. I did so much to the car last year, that I don't remember what it was that actually resolved the problem. Is there a common problem to this symptom, before I set fire to the whole thing.