There is an idle stabilizer valve, which is supposed to keep = the idle from dropping when the engine is loaded by the AC or power steering. It = is controlled by (what else) a controller - a sort of elaborate (and = expensive) relay. The valve in question lives right on top of the middle of the = engine - it's a transverse-mounted cylinder about 4" long and 1 1/2" in diameter. = It's mounted in a rubber bushing and there are air hoses attached to it on = one end and wires plugged into the other. The thing should "hum" with the = ignition key in the "on" position, engine running or not (it's easier to tell if it's working with the engine off, key on). If it doesn't function, = replace both it and its controller. Even if it does hum, it's not necessarily = working all the time. If these items are old (120,000 miles or more) = you can replace them on principle without feeling bad about it = - they're living on borrowed time anyway. Of course, the ideal is to replace the = parts one at a time with KNOWN GOOD for testing purposes, the hitch being the = availability (or lack thereof) of such things. There are procedures for testing this equipment outlined in the Bentley book, if you're somewhat equipped with = electrical testing knowledge and gear... Happy = hunting!