what year mondeo is it? A friend of mine has been having problems with his car, glow plug light on then started cutting out at random when driving. His has been into ford and they think they have finally sorted the problem after having, new injectors, con rod (one was bent but would still run), fuel rail, connection to fuel rail, new ENGINE and now it turns out the hard casings inside the engine are breaking up which could lead to new injectors,conrods etc all over again on the new engine. This has amounted to thousands in repairs but its a company car under warranty so at least he has not had to pay for them.
Yours could be as simple as a duff glow plug though, is it hard to start in the morning?