Hi Jimmy - welcome to the forum.
As you mention your engine has heater plugs I take the engine is a diesel. The post by Petta refers to a petrol engine.
But if you are having starting difficulties from cold but all is OK when the engine is warm it may be worth checking the engine coolant temp sensor/s. If faulty the ECU
will think the engine is always warm and therefore not adjust fuel and injection timing to suit cold starting.
No gaurantee that is you problem but it may be worth checking if only to rule it out as a possibility.