I'm on my 3rd diesel Mondeo since getting rid of the barge, 2 MkIII's and currently a MkIV, of the same sort of age as the OP's asking, TXS spec so all the toys. Present one is now sitting at 105k miles, but I'm not getting too excited as its due a MOT next month, but its served me well.
All I have ever had go wrong are service type items.
Yes, MkIII's did have a tendency to let DMF's go, but I would that was generally due to folks not keeping the engine at sufficient revs for the speed they were doing. Injectors seemed like a throw of the dice, to see if you got good ones. Neither were ever a problem for me
Will I buy another one, no, but that's only cause I want them to make a real AWD ST version and stick a nice big engine in it.
The thing to remember is that all folks usually go on forums for is to find out cures to their cars faults!!