W246 B Class, rough start?

[leenico121]

Hey good people

Could anyone help or experienced similar problems?

I have a 2012 B class (W246) petrol and this morning it started rough but after 30seconds or so smooths out and runs then engine settles and runs normal only seems to do it from cold?

I'm guessing ignition system ie: spark plugs, coils, injectors, or temp sensor?

I changed spark plugs last year so shouldn't be them

Could anyone give me some pointers it any easy quick checks or fixes to sort it out before I go changing parts

Thanks in advance

Leigh