Overheating and running rough

Check the coolant level to see if it is at the proper level. You might also have air in the coolant system. Did you ignition parts for eh engine get wet twitch coolant? Then that would be the running rough issue. Also depending on how how your car overheated, you might have effected the head gasket or cracked the head. Perform a cylinder pressure test and or leak down test to determine if the that is the issue. Did you change the oil after you over heated? It's usually a good practice to do so, as excessive heat will break it down.

TDolby, My brother did the work for me, as I know nothing about car repair! He stated there is no air and oil is not "milky", is changing the oil and filter. He also said it could be some sort of sensor, but isn't sure?

With the engine cold pressurize the cooling system. The system should hold pressure for 15 minutes minimum. If not, something is leaking. Start the engine with the cooling system still under pressure. Watch the gauge on your cooling system pressure tester. If the needle bounces with the engine running the head gasket is blown. Hope that helps! Jim