Seen someone post about their car starting bad when it's cold. I'm having the same issue whereas mine is diesel and the post I seen previously was for a tfsi. My car is a 2008 a3 tdi 170bhp version. It starts fine and runs fine once it's warmed up even the slightest bit. But once it's been sitting overnight when I start it in the morning it idles very rough for probably only 2 or 3 seconds but it's just annoying. It sounds like a tractor, really loud for that first few seconds then settles down and it's fine, doesn't idle rough after that and it drives fine too.
any ideas what's causing it? I'm thinking it's maybe just needing a set of glow plugs?