3.2 Tickover Problem

Hi, I have a 3.2 A3 Quattro Automatic on a 54 plate. When I start the car up it idles fine at around 600rpm but as soon as I touch the throttle the rev count jumps from around 400-800rpm and is very lumpy. It sorts itself out when I get going but does it again whenever I'm at the lights or in traffic.

I've changed the plugs and coils so I'm unsure of where to go next. Any help/advice would be much appreciated!