Ok, finally getting somewhere I think with my on going fault of having no power below 2k, then all fury and a cloud of black smoke! Bought a new MAF sensor today (Bosch one) no difference. Starting to get a little hacked off, so trying all sorts of things I had my foot buried on the throttle in 4th, at about 25mph going up a slight hill, alot of black smoke and it went into limp mode, which to be honest was a brilliant result! Got home hooked it all up and got P2279 as the code. So far (in no particular order) I've done the following over the past few weeks.
Swirl flaps bonded open at the 10 o'clock position
New MAP/Boost Sensor
EGR Blocked off
Boost pipes changed
BCS Filter removed
Throttle Body cleaned and inspected the electrics for any dry joints
I'm coming close to calling it a day, I spent £620 on Friday having the clutch and DMF replaced. Another £120 today on a MAF, plus various other things that have given up on this the past few weeks (air con pump, rear springs, alternator). My gut feeling is to sell it on, and it can be someone elses problem, I use this for my business and doing 50k+ a year I need something thats a 100%, I had a Skoda Superb 1.9TDI before this that I did 50k in, and apart from a £9 coolant sensor it never gave me any trouble on this scale. I changed to the veccy as it looks a fresher car, I had an estate before as a company car and loved it. But before I do is there any other suggestions on easy things to check, turbo's, intercoolers etc is where I draw the line as it starts going into stupid money!