About the fifth time its happened in a year, for some reason every now and then (mainly in the morning) I'll drive the car for maybe a mile and just as im about to go on the power it will go into 'limp' mode where I get a massive loss of power and the car struggles. If I pull over and switch it off then on again it will be fine.

Any reason why this happens?

Sounds like either its over boosting or the vanes on the turbo are sticking which is putting it into limp mode.

Mine had sticking vanes and i had the turbo stripped and cleaned and its not done it since. I also have a mate who had this and he cured it by thrashing the hell out of it for a short journey!

Most likely sticking VNT vanes, as they cause over boost deviation from expected values when stuck. Easy check. Remove engine under-tray, find the turbo (when cold!) find the VNT actuator rod and vacuum unit. The rod should move freely with no tight spots. To check actuator, remove vacuum hose from actuator, and fit a vacuum test pump. Apply vacuum, and again the rod should move freely, and the actuator should hold vacuum with no leak down.

They do a turbo cleaner, Id recommend you use that mate as matt said its sticky vnt

This has now escalated to something more serious - driving along the motorway and started to hear a faint whining sound, came off the motorway and it got worse, whenever I try to accelerate it just whines really loudly and I have no power. Is this the sign of a dead turbo? I've had the boost pipes come off twice this year but this time I cant see anything out of place.

Any help would be much appreciated.

Turbo on its last legs for sure. My went into limp mode once at the top of 5th gear, I must have a small leak somewhere and the values aren't matching up so the car goes into limp to stop itself blowing up.

Yep went to the garage today and the turbos gone, cars done 80k miles (about 8k-ish on a remap) and it does get driven hard. Going to go hybrid but not sure where to buy from? and PD130 or PD150?

Turbo dynamics is the place to buy from, and it all depends what you want from it really. Also consider you clutch in the equation

After looking at the prices I've decided to go with Turbo Centre UK, £540 + my knackered PD130 for a standard PD150.

I don't plan on going over 200bhp anytime soon as I haven't got the money for an uprated clutch, intercooler etc so this is probably the best option for me.

The bloke on the phone mentioned something about blanking off the EGR valve? is this necessary on my 2004 ASZ engine?