Replacing the thermostat and radiator cap it is still overheating

I put a new head gasket kit on my car because it was overheating. I found oil in the water. That is what lead me to believe the head gasket was blown and I believed replacing it would fix the problem. After doing all that work and replacing the thermostat and radiator cap it is still overheating and now it is running rough. I believe the timing is off a little bit. Before I started this job I could hear and feel the thermostat and radiator cap opening and closing real fast when the engine started to overheat. That is why I replaced them. But this continues to happen as well as the overheating. Where do I go from here?