I kind of have this issue too.

The car will sit and idle for awhile, but then randomly, if I give it gas, the idle will hang up around 2800 to 3500 and stay. Looked for vac leaks too and found nothing. I havent dug deep into this problem yet though because I am working the body over on it again, but my fans wouldnt turn on either, so I am thinking I might have a junk ECU as well. But everything else works fine, I have no troubles getting it started and have power to everything else I believe.

Interesting.