Like I said which engine do you have? Reason I ask is just to try and totally get rid of the EGR possibility. The 8V JTD egr valve has a two pin connector, you can just disconnect this and it should drive fine but with the yellow MIL light on, and on the 16V has a 3 pin connector, the extra pin provides position feedback to the ECU, I don't know how it would drive with this faulty/disconnected. I honestly don't think it is the EGR valve, but it could be slightly different if you have the 16 valver.
A good clue for the hoses would be if you get someone to rev the car with the bonnet open, you should easily see the hoses swell with the extra pressure from the turbo.
In the dim dark past I can remember some people on here reporting similar symptoms that needed the MAP(manifold air pressure) sensor cleaning. This is a square black block on the back of the intake manifold with aan electrical connector to it and one bolt holding it in place.
Failing all of this ask someone on here that lives close if they can run ECUscan for you on the car, loads of people omm here have the software and leads, you could even get it yourself for £50 + the leads off of Ebay.