Overheating?

Okay so, I have no smoke coming out of the tailpipe, no milky residue in my oil, no burn out spark plugs. I change the radiator. Change the thermostat, change the water pump, change all of my tubes now my car is holding off a little longer while driving and not overheating. It takes about a half hour, but then the overfill tank the reservoir tank Starts getting coolant in it and coming to a pressure bubbling pressure so it’s hot and I don’t know if this is because at first it wasn’t anything going in the reservoir tank because my hose was clogged up the little plastic piece that connects the two hoses on the overflow hose. My dad had a drill that out now could cause a problem since he made that whole bigger inside of that plastic connector Because it was so clogged that was the only way getting unclogged and I feel like it might be that hose just in general that’s causing it because I do see black specks in my coolant so I think the hose might be deteriorating, but I don’t know if they keep telling me a head gasket, but it doesn’t seem like it cause I’m getting no head gasket Symptoms except for overheating please help this is been going on for four months now and I can’t figure it out.