Thanks for all suggestions, I've found the problem. After I replaced all 20 year old brittle rubber fuel-lines with stainless steel lines there was a vacuum leak at the oil filler cap, after repairing it everything runs great. Klaus Steiner VIN#05980 -Germany- www.steinerklaus.de > Date: Fri, 13 Apr 2001 13:09:02 +0200 > From: klaus.steiner@xxxx > Subject: idle problem > > Hi group, > > Following problem occurs: > My engine idles between 500 an 1000 rpm when warm, idle speed > microswitch works. When I press the full throttle enrichment microswitch > the frequency valve changes noise and the engine idles at 1000 rpm. Any > suggestions?