vacuum pump on a td4

Problem with servo assist on brakes, after it has been stood for a few hours as you set off the servo dies. It seems that there is pressure left in the servo at the start then the peddle goes hard after 20 seconds or so the brakes are fine again and no problem at all when driving. Have checked all the hoses and can see no problem. Thought are that there is a fault with vacuum pump, but before changing it has any one had the same problem. 2003 plate td4

replace yer vacuum filter yer daft numptie

Cheers Ming, should have said that it has been replaced, only thoughts are knackered pump, but wonder why once it has built up pressure it fine

Check all the vacuum hoses for egr and turbo boost control for chaffing.
It seems as though there is vacuum stored in the servo but not in the other systems the vacuum pump serves until the pump can catch up with pumping the air out.