hi guys! I’m new to the forum and really need help figuring this out. First to start off I want to say my car has downpipe, full exhaust, no cats, upgraded intake, and an apr tune. I replaced my diverter valve, also did a smoke test and have no leaks whatsoever. Now to get to the point, ever since I bought the Audi from previous owner I’ve been experiencing this problem and I took it to many shops and no one seems to know exactly what’s going on. But when I start my car in the morning and let it warm up and I take it out for a spin the first 5 minutes or so the car runs fine and goes into full boost. Once I sit at a stop light or park the car and let it idle for a minute or two the car out of no where won’t go into boost anymore and car feels slow as hell. Turbo is spooling but car not going anywhere. Then when I’m on the highway and drive into 5th or 6th gear for a while the car boosts again without no problem and as long as I stay on the highway with my foot on the throttle the car will go into boost just fine, but second I get off the exits and stay at a stop light or let my car sit idling for a minute or so it acts up again and feels as if it doesn’t want to go into full boost. I maybe get 5 psi out of it if that. If it was the turbo the problem or boost leak I wouldn’t be able to make the car go into full boost on the highway. So I’m guessing it can be the high pressure fuel pump going out? Any idea what it can be anyone? I’m new to the German car life lol