so i recently bought a used 2003 audi a6 from a dealership, week later the engine light comes and and the code reads emissions-purge valve ect, something like that i forget. now when im driving ill get up to around 2000rpm and the car will start making a lawnmower/cards in a bicycle spoke type of noise and when i go higher the noise gets louder and faster, its litterally driving me insane. i dont even want anyone in the car, it sounds like absolute ****!

now when im in PARK or NEUTRAL the car and i rev it up past 2500-5000rpm the car sounds great, absolutely no noise at all! only when driving does this noise occur. could this be from a bad purge valve? i took it to a guy recently who said it was a lifter but i have read that a lifter and a bad purge valve sound very similar. when i bought the car it wasnt making the noise at all. so mabey i could be in luck with this one...

any suggestions?