I have written to this forum some time ago with related to this rpm drops (hiccup) on my audi a4 1.8t. (2002)
As some of the guys advised me to go and get checked my pcv system, vacuum tubes as these might causing problems.
Audi has already changed the air mass meter and cleaned the throttle body when I first came up with this problem and it still exists and audi keeps telling me there is nothing wrong with the car.
I am bit puzzled here as I know there is something wrong and audi is telling me its not. Also I was asked to leave it like that bring the car back if the problem gets frequent (at the moment it is intermittent) so they can check it straight.
I also noticed dripping some oil from the air intake hose and showed the audi and I was told this is normal again. I was bit scared this is due to a malfunctioning turbo unit.
Please can some one help me in this situation and I really appreciate ur help.