Does my 2013 Holden Cruze have a transmission control unit issue?

Yes, it could be something to do with the way the transmission is behaving. But it could also very easily be any one of a hundred other things. A faulty transmission can cause a car to surge while stopped, but so can a fault with the fuel, ignition and any number other systems found on a modern car.

But work backwards for a moment. Did this new problem occur immediately after the plugs and coil-packs were changed? Or was there a full week of normal driving before the new problem set in? I’d be checking the connections on those new plugs and coils and making sure that nothing has been left loose. A poor earth connection can be the source of many problems that seem like something else initially. From there, I think an electronic scan is probably the best advice as this will help pin-point what’s going wrong. The car’s own computer should have a very good idea of what’s amiss and can alert you to it quickly.