I have a problem with power loss now and then on my mondeo turbo diesel, like the turbo cuts out then in again

twice recently it has drove for a short distance like just diesel,no turbo,, on its usual day it drives ok but the turbo actually jerks on and off at around 3000 rpm...it revs past this and goes ok, on the motorway i can actually find a place on the revs(say 4th gear at 65mph)were the car car feels like you are pulling the handbrake on and off, like the turbo is in and out constantly, it revs past this no problem..today the turbo went out completely for about 2miles...it never smokes, not even when this happens,,,ive been told that turbos are not realy complicated and if they go, it is usually seals and you know instantly...its been suggested, air flow meter,,,a flange split,,,diesel filters,,etc.. but im realy skint and could do with a pinpoint answer(a lot to ask i know)...ive thought about changing the full manifold with turbo, full air filter etc, oil cooler the lot, local scrapman offered me all this at �60, cheap but a big enough job when it could be a simple task,,please help..