Audi Repair: TT Quattro shudders and cuts out on first start, coolant temperature sensor, engine coolant temperature sensor

Question
I have a 2002 Audi TT quattro. When I try to start it, the car starts, then shudders, revs drop and cuts out. The 2nd time it will normally start ok but with a little shudder or alternatively if you give it acceleration it will normally stay started although still struggles a little.
After 5 seconds or so the shudder disappears and the car functions ok. The computer says "OK" to everything and other than this the car drives fine. any ideas what this could be ?

Answer
you state this only happens on first start, do you mean when it is cold?  It could be that the cold start system is not functioning correctly, or a more likely problem is the engine coolant temperature sensor is faulty.  I would check that first.  Jan