Land Rover Repair: Idle speed, land rover discovery, valve cover gasket

Question
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Followup To
Question -
I have a 97 Land Rover discovery with 80K miles. I took it to a mechanic b/c of a oil leak.  He replaced the head gaskets and the leak was fixed. The only problem is now he can't get the idle speed back to normal (below 1000 RPM's).  My idle speed now fluxuates between 2500 and 3000 RPM's.  We tried a new airflow sensor, and that didn't fix it.  There is no tension on the accelerator cable, and it is routed properly.  There are no air or vacume leaks.  It's like the engine is getting way to much air.  If you restrict the air flow to the engine with your hand, it will idle properly. Please help if you can we are at the end of our rope. Thank You Steven.
Answer -
Hi,

I need to know if the head gaskets or the valve cover gaskets were changed. The rovers have had intake manifold gasket problems resulting in this. Another cause could be an Idle Air Control Valve. This controls the Idle. and needs to be calibrated afterwards. Get back to me with any problems
Thanx, Dave

Hi Dave,
Thank's for your quick responce. It was the valve cover gasket that was changed, but the Idle Air Control Valve was never calibrated.  Where can I find the calibration procedure?  This sounds like the most obvious place to start.
Thank's, Steven

Answer
The IAC "Idle Air Control" I actually calibrated via a test book from rover. The unit is mounted where the intake hose goes in the engine. Black small bulbous shape,with a 3wire  connector protruding 90 degrees. Mounted with 2 screws. You can remove it and cleaning the IAC with some Carburetor cleaner will help maybe. I suggest a new component. These fail all the time, Cleaning it will help for a period of time if you are trying to sell it.

Thanx, Dave