i have a '03 Jetta GLS with 1.8T. it has a weird problem, on cold starts it idles really really rough and makes a high pitched noise, so high pitched it almost sounds electronic. it will run like that for about two minutes (and if i start driving, it will stall if i put my foot on the brake while it's in drive), after two minutes of running, i assume it's from warming up, there's a big loud depressurizing noise, and then it runs normal. it has no engine light, no fault codes, two vw techs told me they don't know what the problem is. i thought it had something to do with the turbo binding but they said it couldn't be. it's definitely restricted air of some kind but i don't know enough about turbo engines to figure it out. it's been happening for about a year with no other subsequent problems. has anyone ever had this problem, any clues out there? a sensor? a valve? something?