An activated, titanium-based, spray-dried Ziegler-Natta catalyst system containing a titanium-based Ziegler-Natta catalyst, a carrier material, and an activator mixture comprising an effective amount of an activator mixture comprising triethylaluminum and diethylaluminum chloride for producing a substantially uniform comonomer composition distribution. Also, polyolefins; methods of making and using same; and articles containing same.