Hi, if you are going to purchase a new Maf sensor make sure it an original one, I bought a cheap ebay one and it gave me more problems, the misfire could be the spark plugs if they haven't been changed recently, unfortunately the sensors can go bad easily with the TT, I had the red oil light on my dash, I changed the oil pump and pick-up pipe and it didn't fix it, I then bought a oil pressure sensor, it solved the problem, the sensor was only £15, the TT likes to test us 🤣