p3arc3

hi I have a audi a4 2009 b7. for the last few months there has been a rhythmic thudding noise from air box on idle (driving me nuts!) the power is also slight decreased. it has been in local garage but they couldn't find an issue. I have changed EGR valve, MAF sensor, did a DPF region, oil+filter, air filter and engine carbon clean but still hasn't fixed the issue. it has 70,000 miles the car. if anyones got any ideas on what to try next please let me know! Cheers