The jumping idle. I had the pleasure all winter long. I finally tracked it down to the fast idle thermo valve... I replaced it with a decently new junkyard throttlebody, which included a newer, factory set throttle position sensor(an integrated part of the TB), and the thermovalve, which sits on the bottom of the TB on my 93 h23. Slap on a new one or try taking apart the old one, here is an article to help you Fast idle valve mod

Bruce