My car had it's 56k service 2 weeks ago, and I had complained about the car feeling sluggish, esp on pull off on an incline. I had thought it might have been the multitronic. Got the car back, and they said they replaced a faulty PCV, and the car definately felt better. Last week thursday on my way to work, I put my foot down to overtake, after hitting some slower moving traffic, and absolutely nothing happened for what felt like forever, but it was probably closer to half a second. After that, the power suddenly came in as my foot was still on the accelerator. I scanned the car, and there was only 1 code P0507. According to the Google, this is cause by the PCV, so I cleared the code, with the intension of seeing if it came back. Car was still hesitating the whole weekend, and today I managed to get through to Audi, who scanned the car and they picked up no errors. Car is booked in on the 15th, so not much I can do till then. One thing I did notice on the weekend, which I've never noticed before, is that if I let the car idle for a few minutes and then turn off, there is a hissing sound coming from the right hand side of the engine bay (looking towards the rear of the car), but it's not the PCV. Sounds like it's coming from further down in the engine bay, but I can't really locate it. If anyone can lead me in the right direction, I'd really appreciate it.