Nissan Repair: occasional difficult start, rough idle, Nissan sunny, leaky injector, nissan sunny

Question
Hi, I have a Nissan Sunny inspiration 1.4i Twin cam 16v, sometimes it takes about 10-20mins of cranking before it fires up, but sometimes it starts straight away. after a difficult start, it will not rev cleanly from idle - it just cuts out if press the accelerator. I have to let it run for about 20mins then it is perfect. recently changed spark plugs, oil, oil filter, and air filter, I checked HT plugs are securely connected, what else can you suggest?

Answer
Nab,

Check the fuel pressure.  If the car takes this long to start and it stumbles when you start it you probably have a leaky injector flooding the engine.  Pull each plug and find the one that is really black.  That is a clue to the cylinder(s) that might have a stuck injector.  The fuel pressure will drop off suddenly upon shutdown.  If the injectors are good the pressure will remain for a while after shutdown.