GMC Yukon

Ok, I bought a 1989 GMC Suburban for $300 from a guy I know, at first it was missing, so I changed spark plugs and wires. Then it was leaking antifreeze, so I changed my water pump, then noticed when changing it that it wasn't the water pump that was leaking, but instead it was my radiator. So I replaced the radiator. Now there's no leak, but now white smoke just ROLLS out of the exhaust and tends to overheat, im guessing its antifreeze leaking into the exhaust somehow. It also runs kinda rough like it doesn't act like it wants to stay running when ideling. Any suggestions?
February 17, 2006.

You are dealing with a blown haed gasket. The antifreez is entering the combustion chamber that is your white smoke. That will also couse the overheating problem. Exhust gasses are entering you cooling system creating air pockets so the coolent does not flow properly

Feb 17, 2006.
2003 Chevy Malibu overheated Changed themostat had it flushed and still overheated. Replaced thermostat again and ECT sensor. Now white smoke out of exhaust and rough idling and check engine light on

Apr 17, 2012.
White smoke usually indicates coolant is getting into the combustion chamber. Most likely, it is a bad head gasket.