Can someone help here please, i'm pulling me hair out. ive got a squelling noise on my engine, this what ive tried so far.

Ive replaced timing belt and tensioner
Alternator drive belt
checked for anything catching or scraping etc etc

ive run the engine with the alternator belt disconnected and it still does it, the noise itself is like a chirping rotating loud noise, like a fan belt slipping, but its not, its allot worse when the engine is hot, but only does it on light accelleration and over run, on hard accelleration and full boost no noise at all, it wont do it when stationary ether you can rev it as much as you want it wont do it at all, as soon as the car is moving it starts, i think its load related, there is no power loss and the car runs 12psi boost with or without the noise, its just friggin embarrasing as hell.

The cars a sapphire 4x4 on a J plate green top and has been stood for over a year,could it be anything on the turbo side like actuators or owt like that, its ahd a recent service as well but nothing changed there.

anything siezed that i could check that might make an noise like this you can think off, please help me its doing my head in now.....