Engine Not starting

How often do I have to change the fuel injectors on my Rover 45 1.8 automatic year Dec, 2000, it has done 66k miles, it runs fine except on kick over it runs slightly lumpy but at the right kick over revs, just passed MOT recently re the emissions etc.

My car has done 66,000 miles and has had cylinder head replacement, it was running slightly lumpy on tick over before head replacement and still does the same, it runs great apart from slightly lumpy crank over even though cranks over revs are spot on, I wondered if it could be a faulty fuel injector.