Does the misfire occur randomly or is it there all the while? If you have the chance I would hook up to VCDS and look at the live readings if possible.
However, I used to have a misfire that would occur randomly and it generally used to happen when cruising around 2500 - 3000rpm (that was most of my route driving between those values) and I sought advise and changed the ECU relay. That seemed to do the trick, no misfire issues ever since.
Some people have reported issues with the fuel pump relay causing similar. But to prevent unnecessary spending, check the basics first and swap components over from known working vehicles if you can.