Hello everyone, new to this forum. I have had a issue with my car. My local garage diagnosed that i had a P0601 error showing on my ECU. I went to Audi who told me I have to replace the ECU. I found a company that do this and I got a new ECU fitted. The problem is still very apparent while driving the vehicle. This is what happens: 1. The car seems un-responsive as if its in limp mode 2. When the revs reach around 2,500k the car shudders and wont boost, this persists through all gears. 3. It feels like the car is shuddering and is also backfiring I have had the new ECU checked and there is no errors showing. I'd really appreciate any response or information anyone has. If there is a mechanic on here that knows the problem, please contact me as I really need this problem fixed.