I have replaced all suspect rubber hoses and inspected all vacuum lines and joints and can find no leaks. My economy guage is now behaving normal again after replacing the hoses but my idle problem persists. I have thoroughly cleaned the idle control valve and even installed a replacement valve but no change. I checked the voltage to the valve when idling and it reads 4 volts so I think that would mean the over voltage relay is working. I replaced the idle speed controller but that did not fix the problem either. I sprayed carb cleaner over everything obvious while idling but saw no change. I am thinking that I might have to remove the intake because I heard that there are 8 seals under there and they could be the problem. I also heard that the problem could be the throttle switch having failed or needing adjustment. How does the throttle switch adjust? Does anyone have any additional advice? The car idles at 1200 in park but idles perfectly normal in drive with no other symptoms.