Is that a QG engine? We don't have a 1.6 here so no experience with it, unless it's a QG16DE or something as we have 1.5 and 1.8 versions. Usually symptoms like that are caused by a stretched timing chain, but you could try swapping the cam and crank sensor and see if it makes a difference. If it does then you'll need a new sensor. Any codes being thrown up?