I'm not too sure where it is on the Q4, but I have found the original artical that I used to solve my problem.
Here it is:-
Stumble when Cold
From: Tony Wood
Date: Tue, 05 Aug 1997 10:42:08
Subject: Re: stumbling 164 when cold
>My 1991 164 with 94,000 miles has developed an odd quirk. When the motor
>is first started in the morning, it acts as though it wants to stall. If
>I try to engage the clutch it will stall unless I apply enough accelerator
>to overcome the attempted stall. Funny thing is that after almost
>stalling the engine seems to "catch itself" and the car is ready to run.
>The computer identifies no problems and everything else seems fine. Anyone
>out there with any ideas as to a cause??
Please forgive if I quote a previous posting, but it may be simply
>>Sounds like it could be the idle control valve. This valve is at the
>>back of the airbox (the big alloy box across the top of the engine on
>>fuel-injected cars), near the firewall. Its function is to admit air
>>to control slow running speed.
>>Identify it by tracing a 3/4" rubber tube from near the throttle
>>butterfly to the valve, which is made of alloy, is about 2 1/2"
>>diameter and 3" long, and plugs into the back of the airbox. There
>>is also an electrical connecting plug on the end of the box opposite
>>the rubber tube.
>>Disconnect everything and remove the valve, which is held in place
>>by a simple clip and 10mm bolt. Squirt carburettor cleaner aerosol
>>into the hole on the valve where it mounts to the airbox, put your
>>thumb over both holes and shake. Drain. Repeat until the fluid comes
>>out clean (clear and colourless). I find a squirt of WD40 inside
>>helps. Then remount the valve, renewing hose-clips if necessary.
>>This saves you a chunk of money (because the valve is not cheap), is
>>risk-free, and works almost every time. Console yourself with the
>>knowledge that BMW owners (identical system) consider this a routine