Me again !!

If you push her hard the turbo pulsates , you hear and feel it spool up and then it dies off then builds up again. Under normal driving the turbo boosts fine ?

Could be any number of things, boost leak, worn turbo actuator, boost control valve.  What mileage has your car done?

She's on 182,000

I think this may be related to your "squeak" thread; When the "radiator" (actually an air-air intercooler for the turbo) moves, you're dropping boost pressure.

Yeah , thought it was maybe an inter cooler. As its not moving n squeaking anymore I'll give her a thrash tomorrow !