I also solved the problem with mine.So after 2 weeks since doing the tensioner and gasket mod and cleaning the MAP sensor the engine runs and sounds much better and no more start up rattle, even from cold. It's a tricky job and alot of it by feel as you can't really see behind the Egr valve but it's a do-able job and worthwhile. The small steel pipe from the egr to inlet manifold was full of oily gunge and so will the inlet manifold I imagine but I'm not taking that off !!
Sold it, so now it will be someone else's problem (Sold it to a Vauxhall dealer, they will know about the problem, so if they sell it on without fixing it, it will be them, doing something bad )