2012 Holden Captiva is running rough when cold

Any remedy can only be suggested once you know what’s causing the problem. The first step, then, is to have the car scanned to see if there’s a problem the on-board computer has identified and logged. Once you have that information, you are a lot closer to knowing what to replace.

Logic suggests that an engine that runs roughly when it’s cold might be running lean. If that’s the case, it could be caused by many things including worn injectors, a lazy fuel pump or even a temperature sensor that is not telling the computer that controls these things that the coolant temperature is low and the engine needs more fuel to compensate. Then, once the engine has warmed up, the fuel-air mixture is correct and the engine settles down and runs properly. That said, 30km is a long time for the engine to take to warm up.

You could spend lots of time and money replacing the wrong bits here, so a scan is definitely the way to proceed.