Probably your oil seals in the turbo are shot.

 

so went for family day out motor way driving. driving 20 minutes and car goes into limp mode no power so pulled over on hard shoulder and i leaned on bonnet thinking about my options because like a plonker didn't get break down. anyways the bonnet was that hot it burned my hand so popped it open left it for half hour all jumped back in and set off and car was fine. on way back 3 limp homes engine really hot again fan wasn't kicking in and temp gauge was half way. so waited like before and car was fine. someone came around and put it on scanner the fault was with ECT thermostat or coolant temperature sensor so I've replaced cts and car seems fine so far ive got the thermostat but its tricky to get it in one this particular engine so thats a job for a professional.
from what I've read the CTS is one of the important parts it tells the engine how much fuel to use when its hot and cold so it can cause smoke. turbo seems fine plenty of power.