Did bringing up the idle fix cooling issue? If I'm not mistaken that would suggest not enough airflow, have you checked your dan clutch?
Good point. But i dont have a fan clutch, it's a rigid system. And no, it didnt solve the problem. It just delays the symtpoms. It might be the carburator, and i'll change the plugs as well. And i'll check the coolant temperature with a guage, as i only have an idiot light on the dash (which doesnt come on when the problem arises)