hope im posting in the right forum now...

I have a problem with my 2004 A4 Avant 1.8T quattro
I have problem with my Turbo / Boost and it started 2 days ago...
When the engein is started it boosts ok for like 100 meters, but after that the boost is about 0.3bar and runs like crap (it should be around 1 bar chipped with GIAC)

The engein sounds normal, but i miss the Turbo sound when boosting... it feels like i dont have any turbo at all...
But after approx 5-10 minutes on driving i have normal boost again and al seems like normal... good boost and nice turbo sound...
When the boost returns (after about 10 minutes) it doesent come suddenly like an punch, more like you accelerating on second gear with boost of 0.3 bar and when you put in the next gear i suddenly have all boost again... and after that it works like an charm until it stands over night.. then the same thing again

On more thing that i dont know if it has anyting to do with this is that when im standing still (no gear) and reving up to about 2800-3000 rpm i have a rattling like fast metallic rrrrrrr from under the car ( i think) .. hard to explain a noise but like someone in a house is drilling in concrete wall with an small and fast drill (electric screwdriver)

The car is chipped with GIAC
The DV is changed to an reinforced bosch valve
The sparks and coils are changed...
The car works like and charm exept this now

Any one got any ideas what the problem can be and how to fix it???

Thanks!
Best Regards
Lars
Sweden