2005 Audi A4 2.0 Issues

Anyone have any thoughts on what would cause the engine to make a wheezing sound at low RPMs. I just had a significant amount of service on my 2005 audi A4 2.0 which included a new battery, spark plugs, fuel injection service, replaced front and rear brake pads and rotors, and coolant system repairs. Now, 50 miles later the engine is making an awful wheezing sound at low rpms, but not while in idle. Any thoughts? Thanks.