The car selects gears fine and pulls fine. however when im accelerating and i come off the gas it makes the noise and if i put the clutch pedle down it sounds like something spinning then stops. if i then raise the pedle it comes in again but as soon as i put on the gas the noise stops??

When chaing gear, for example going from 3rd to 2nd, when the clutch is down and i select 2nd, the noise happens for a very short period of time like a little blip, then goes. If i then raise the clutch to engage into 2nd gear i get the noise back.

Any idea? its really starting to annoy me that i cant work out what it could be

cheers