Hello, I hope I can offer you some assistance.
Which engine is fitted, petrol or diesel? What size as well?
Let me know and I'll reply as soon as I'm able to.
ford smax zetec tdci 6g 1753cc diesel
Hello again, thank you for your reply.
There are a few points to check that are quite common on this engine that can give the symptoms you describe.
Check the wiring to the injectors where it comes over the top of the engine, it's common for the loom to chafe on the valve cover near the camshaft position sensor.
Check that there isn't a problem with air getting into the fuel system although if this were occurring I would expect the poor starting to be more regular.
Have the engine management control module (PCM) checked for any stored fault codes that will identify which sensor or actuator is giving the concern, most garages can do this at minimal cost but if you want to do this on a DIY basis then a cheap code reader is available on the internet for around £40 an example is http://www.ebay.co.uk/itm/Sealey-VS8700-Sealey-EOBD-OBDII-Vehicle-Diagnostic-Fault-Code-Reader-Scanner-/360554662816?pt=UK_Diagnostic_Tools_Equipment&hash=item53f2bb8ba0
If you decide on a garage checking this then use a garage that can update PCM software as it's not unusual for a software error in the PCM to cause this so the PCM calibration needs to be the latest level available.
Start with these points, let me know if I can assist further or if you have more questions regarding this and I'll reply as soon as I'm able to.