Engine Revs Dropping At Open Throttle

[ardie]

recently my car has started to do something strange. ill be driveing along in 4th or 5th gear sitting on around 2 and a half grand, and then ill floor it and itll rev up to around 5 grand and then start to decline till it hits around 3 grand, where it will then start 2 pick up again. its not a problem with the tacho as i can hear the engine revving in accordance to the tacho reading. it has only just recently developed this, and it only does it in 4th and 5th gear. any help woul;d be much appreciated

thanks

ardie

[RB30-POWER]

very simple.

its the clutch stuffed.