Won't idle when cold .

OK , my 96 1.8 a4 , when dead cold , starts , but wont idle when cold , holding it about 1500 rpm it will die then just about 500rpm it will come back up to where I am holding it . A good blip on the throttle will clear it for a short while . But only after 1 or 2 mins of running time it will be fine , idles ok ( idles high at operating temp , 1200 rpm due to somebody putting a cable tie under the throtttle cable clip )but dosn't pulse .
Now , I have had abit of a clean of the throttle body , got as much of the crap out with brake cleaner and a rag , but am tempted to get back in there and have another go and get the compressed air down a fewof the ports I can see . Wise idea ? Other than that am thinkin it can only be an electrical fault , dodgy cold start temp sensor or something . Not fully up to speed on audi engine managment stuff yet .
Any help appreciated ,
Cheers Cam

Cheers , Yea , have posted on the vag.com forum asking for sombody in my area . Whats it worth if you want to sell it ?

Cheers , have friday off , so will be goin somewhere to get this thing diagnosied ,think there could be a couple of other things checked , then off to where I work to hijack the host for the arvo , have an exhaust leak to weld up as well .

Well 10 Pts to SteveU , had my codes read , coolant sensor was one of the faults that came up , the others were faults that related to the coolant sensor . So one £15 sensor later and 5 mins to fit it , job sorted !