Hi, I've got a 2005 A4 1.8t Cabriolet (70k on the clock), remapped by Celtic Tuning several months ago. For a while now I've been experiencing a strange problem and cant seem to rectify it, every so often the turbo simply stops working?!. When it happens theres a noticeable lack of power. I've found the only way I can get the turbo working again is to unplug the MAF and start the car again, wait for the error light and then reset it via the OBD. Plug the MAF back in and start the car and the turbo then spins up and works fine. When the turbo is working the car seems to run out of power approaching 85-90 and then the turbo will stop again. I've also noticed that the car wont change up from 4th to 5th automatically (its the multitronic box) under hard acceleration so I have to manually change up. If I accelerate a bit quicker the ESP light comes on for approx 10 seconds then goes out, this isnt due to the wheels losing traction, it does it in all conditions even on very dry roads on hot days, I am not accelerating with my foot flat to the floor. I've replaced the MAF (Audi unit not aftermarket), Forge DV installed, new plugs and the pre-cat lambda is being done in the next few days. Any ideas what it could be, I was wondering if it could be a bad remap but Celtic Tuning state it definitely isnt..... Any help greatfully received!