Warmup hiccup

[HJS]

Ever since the day I got the car (+/- 10 years now) it hiccups in warmup. The 
car runs perfectly, starts right up, runs strong, but on these really cold 
mornings it has a hiccup. When I start it on a morning like this, all is well 
and normal, drive down the road, its all good. A couple miles later before it 
gets fully warm, its like someone hits a switch. Everything dies, tach drops, I 
hear the fuel pump relay etc, but only for a microsecond then it all comes back, 
never to do it again for the rest of the day. Obviously its not a big deal, Ive 
been living with it forever, but my luck will run out one of these days Im sure. 
Anyone seen anything like this? Vag com shows no codes. Since its still cold, it 
doesnt see any boost, or anything strenuous, just more or less idling along down 
the road.