380 DB Series II 2006

a very recent problem ive got with my 380 is that it wont accelerate over 4000rpm.
if i pin the pedal to the floor it work great until the tacco reaches 4000rpm then the car acts like its chained to a house. if I carefully drive and not let the revs build up to the 4000 mark it drives fantastically
and it drives off into the sunset without a problem in the world.
any ideas, oh and its not the gearbox ive had it checked already.

Cheers