howdy all - i am going thru a bit of high idle hell and hopefully, someone here can help me out. I have an 85 380se euro car that developed an intermittent high idle after warm up. in park, it would idle @ 1800rpm and in drive it would be at about 1000rpm. sometimes it would go back to idleing just fine (600ish rpm) for a while, then it would jump back to high idle without warning. i have searched thru the different threads here and got some great information that caused me to do the following:
1) i replaced the idle control unit with a rebuilt one. the rebuilt unit has an idle adjustment screw that has allowed me to lower the idle to 1000 rpm - definitely better but still not right.
2) new ovp relay. mine rattled when i shook it so i spent the money and got a new one. no difference.
3) i got a different idle air valve from the junkyard to see if that was the problem, and this is where my question comes in. when i unplugged the air valve, with the ignition "off", i felt power going to the valve and i heard the valve close (or open?) when the plug was disconnected. when i put my meter to the plug (the car is not running, the key is in the off position and the engine is cold) i get 12 volts. why am i getting 12volts??? what regulates the power to the airvalve?

i feel i am very close to fixing this problem but i don't know where to look next - any help would be greatly appreciated.
thanks