hi mike, this is what i've recently done to my car and it has improved the idle loads, it looks loads harder then it is to do, first i used a restricting gasket on the EGR/Intake Valve or throttle valve, (not sure the Technical name) but its located on the end of the inlet manifold, (will get you part numbers when i get home, all OEM parts from audi) you'll see in the pic, (click to enlarge)
when you remove this you'll notice a build up of loads of crap, mainly because of the EGR system, my car has only done 57000 miles and this is what it looked like, hard to see tho as i took the pics on my phone,
as you can see its full of crap! next thing to do is clean all this out, using brake cleaner, or anything that will budge the stuff, but as you'll notice in the next pics, if yours is like mine the casting was shocking, and left quite a big lip on the inside, looks as if it wouldnt do much but it can affect air flow by alot,
using fine emery cloth, and a dremel i started filing that lip back, until i was happy it was smooth,
as you can see its quite a big difference, putting it all back together i replaced all gaskets i had removed, but the EGR gasket i replced with a Updated gasket, as i said earlier when i get home i'll get you the part numbers, all can be bought from audi/vw/seat and so on,
but with the gasket itself you'll noticed i've drilled 4 3mm holes around the center hole, this is because if you restrict the EGR valve to much it'll bring up a Warning on the dash, and also (heard this as a rumour) blocking it off completely it will still run fine, but apparently can cause the turbo to overheat if you have a heavy foot, i'll also put the pic of the tools i used to get the EGR/throttle Valve off,
"above" the updated EGR valve gasket with 4 3mm drilled holes,
"above" tools used to remove the EGR/throttle valve thing..ie
was a really easy job, looks scary but honestly its not to bad, one problem you might get is the two bolts to remove the pipe that conects to the EGR valve from the exhaust manifold (soild steel pipe, round the top of the engine, near the bulk head) are a very weird shape, unlike allen key or torx, it has more splines then them, luckly without even knowing i had the correct tool bits to fit, but i'm sure you could use an allen key without causing to much damage,
doing all this as i said improved it loads for me, and i hope this helps, if you need a more detailed description message me, this is just a quick one as i'm at work haha,