Hi guys after some help having a nightmare with my tdci 1.8 Ford Focus.

started by cutting out just after starting engine malfunction light the lot took to garage egr valve got changed, done it again code came up egr value so changed again just in case fault with new one. Worked fine for a week, happened again got the injectors tested and fixed ran fine for a few weeks. 

Then orange engine light comes on running fine then engine malfunction lights come on doesn't cut out goes into limp mode got alternator changed worked fine for 2 days then engine malfunction lights comes back on while driving and goes in limp mode.

any ideas could scream spent a small fortune on it as I haven't got a clue about engines 

Get the fuel filter checked.
They have a habit of getting fouled up.
I recommend a new fuel filter at every service even though it's not usually done on a standard service.
Ensure it gets a new filter housing seal as well as they sit properly if reused.

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On 12/9/2017 at 6:36 AM, Grahamwilli said:

started by cutting out just after starting engine malfunction light the lot took to garage egr valve got changed, done it again code came up egr value so changed again just in case fault with new one. Worked fine for a week, happened again got the injectors tested and fixed ran fine for a few weeks. 

Then orange engine light comes on running fine then engine malfunction lights come on doesn't cut out goes into limp mode got alternator changed

I suggest trying either a better garage, or get a good fault code reader system like Forscan, and use Google & sites like this one to learn what the codes may mean.

The garage seems to be changing random bits at your expense at the moment. Changing the EGR on a 1.8TDCI is a massive job, probably about £800 at a garage. If it was less than that, then they just changed the EGR actuator to a cheap non-OEM one (I do not think there is a proper Ford replacement actuator). For an (excessively!?) detailed lot of info about the 1.8 EGR valve see:

Being able to read the error codes as they happen is very much more useful than taking it to a garage some time later, and hoping they can guess what the problem was. If warning lights are coming on, there will be potentially useful codes stored.

Without those codes, there are loads of possibilities. The 1.8TDCI certainly is sensitive to air leaks into the fuel system, or clogged fuel filters, like Clive suggests, though these most likely happen on starting, or maybe on heavy acceleration. But that is one of many possibilities.