1.4 Petrol Fiesta MK6 Chugging

[melissafaith]

Hello, wondering if anyone here has experienced similar problem? 

My fiesta- 2007, has always made a chugging noise when first starting in 1st and 2nd gear, usually the noise goes away once the engine is warm however this last week the noise has remained even after the engine has warmed to usual operating temp & I can now hear it all the time and its loud enough for other people to notice. As the rev's increase the noise gets faster but only when driving, I can't hear it in neutral and apart from occasionally not starting, the car is otherwise fine. 

Its had a new clutch and cambelt recently, along with a slave cylinder. Any ideas?

Thanks!