mk3 golf tdi gl loosing turbo boost smokes real bad.

Hi I am new to the site but a previous vw feak with 20 mk1 golfs and about mk2s to my name in the past, Due to clocking up 40k a year I bought a cheap car to commute from swindon to north worcesterhsire every day. bought an m plate 1.9tdi gl m reg golf that has been parked up for 12months. owner said it wouldnt start and when it did it ran very badly on 1or 2 cylinders. I bought a brand new high output battery went to pick it up and it started with no issues at all. no smoke etc. the engine was warmed before revving. drove the car on trade plates back to a garage to go for an mot to see how bad it failed. on the way to the mot station it wouldnt drive quicker than about 70 and wouldnt pull the skin off a rice pudding.... it failed on emissions when the rev test was done and filled the mot bay with clouds of smoke. My guy in the mot station said it had smoked out the bay. got it back to my unit after it failed and it drove fine just woudnt pull 65-70...

it dawned on me that the fuel was very old so filled it up with 2 gallons of new derv... if you rev it through the rev range through to five grnad ish taking 3-or 4 seconds to get to 5000-5500 it runs absolutely fine, stationary. but the second you rev it whilst warm of course straight through to 5250/5500rpm it drops onto 2 cylinders and pours black smoke out the exhaust.
restart it and it idles abslutely fine....
dont know much about diesel engines but have heard of egr valves, possible fuel or air filter issue(???? non genuine fuel filters have been known to cause issues????) or boost solenoid, but havent got a clue what any of these look like???
any suggestions welcome as am at wits end and dont really want to blow 300 400 pound fixing it??? car is as you would expect from vw solid, still well screwed together tidy, shame i cant get it going.... help please...???:beerchug:

is there a smell of oil in the exhaust fumes?? it might be the turbo has gone can you hear the turbo whistling when you rev the engine???

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Originally Posted by wingers1982

is there a smell of oil in the exhaust fumes?? it might be the turbo has gone can you hear the turbo whistling when you rev the engine???

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there is oil in the exhaust as it comes out as black as.... when it first did it the ground was soaked with soot....but it cleared. will check next time i get near it to see if the turbo whistles... any idea on a replacment cost?? or is it toast!!?

thanks for the reply...