Zafira diesel loss of partial power and total loss

I have a 2004 2.0dti zafira. I had a loss of power and the limp home light (car and spanner) kept coming on over recent weeks on various occasions. It restricted the revs to about 2800. The car has about 80000 miles on it and I bought it in march. The previous owner said it was used everyday but not on motorways. It had been serviced in December.
I read here that the egr valve is the most common reason for this problem. I removed the egr valve and cleaned it. It was really badly covered in carbon. This seemed to resolve the issue but it started happening again. The next thing was to replace the maf sensor. Before I received the unit to put on the car, I had a complete loss of power whilst travelling on the motorway at 70mph. The car just lost power and slowly reduced speed to nothing and then cut out. After leaving it for about 10 mins it started and drove for about another 2 miles and the same happened. I had to get the car recovered. The recovery guy checked the error code and nothing registered and the car started with no problems.
I have changed the maf sensor now and the car ticked over nicely with no light but when I took it out for a drive it lost power within 2 minutes. As the car came to a stop the engine just about ticked over and I noticed that the air pipe going towards the egr valve was contracted as if it was struggling to get air into the system.

Any ideas on what could be wrong