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possibly.
what model commy is it?
Also is it an auto. it's possible that the auto cooler (part of the radiator) has corroded and allowing trans fluid into the radiator.
Also if it is a Ecotec they are prone to the intake manifold gaskets failing at around 150,000kms which can also do this.
Could also be a head gasket but rule the others out first as they are chesper to fix.
Temp shooting up and down is a sign of an air pocket in the cooling system. Could be caused by a leak, wether from a head gasket, inlet manifold gasket, or just a leaky hose.
Manifold gasket is new so I can rule that out