Why would you pull block plugs? Just take out the thermostat and bolt the housing back on. Drain the radiator and fill with water. Start 4runner and after a minute turn it off and drain radiator again. Do this 3-4 times and it will be clean. Also make sure the heater is turned on so it clears out the heater core. This whole procedure takes only about 15-20 minutes. When done drain the water out of the radiator again and then add half the systems capacity with pure antifreeze.