all engines are the same fuel, air, spark. its missing one or hesitant on one. try back tracking your air make sure everything is clean and good, then move on to spark then fuel. your best option would be to have the car scaned with vagcom to find out what errors the computer is holding. try not to just throw parts at a job its how you get stuck with many expesive fixes. try these few things. 1. Check the psi in the cyclinders make sure they have proper pressure, 2 check the fuel system for presure, check your cam sensors if you have codes look at your list and try google searcheing the codes for ideas of places to look. also try some audi forums boards for help.