Thanks guy for the speedy replies. The injectors as i have said are brand new, the fuel is fresh, the CTS has been replaced for new. I would have thought that if it was a pressure drop in the line it would occur on initial start up in the morning, but its fine then. As i say its only when it has stood from hot for 2 hrs. Left over night its fine. The emissions are correct or were correct when i checked it last. Once its back in the workshop i will test a little further and report back.