What battery is fitted? It must be a silver calcium, a lead acid will screw with the smart charge system and give you errors.

It certainly sounds like a problem with the ISCV or an air leak. Have a good look around for any vacuum hoses that have splits or become dislodged. Spray some carb cleaner around them with the engine idling, if the engine note changes then you have found your leak.

Cleaning the ISCV rarely works, I would probably replace it with new.