The Toyota Engines will run hot if the thermostat fails,or the cooling system is full of debri, rust,or a bad radiator(ALWAYS use the OLD radiator to flush the system BEFORE putting in the new radiator .) or the radiator cap goes bad.The most common problems I have found is the LOWER RADIATOR HOSE will collaps after the engine gets hot and you turn it off then restart it, or in stop and go traffic. In these situations the cooling system will create a vacumm in the system causing the weak sidewalls of the hose to be sucked together,This vacumm in the system is normal in order to pull fluid out of the overflow tank back into the radiator as needed.There are 2 remedies that will cure the lower radiator hose problem,1- buy the lower radiator hose with a coil spring molded in to the rubber of the hose, 2- buy the stainless steel lower radiator hose spring that you put in the hose. When using the SS 1 1/2 spring be sure to put it in a new hose just to save time. The spring can be bought on the internet for about $6.98 and you`ll find it for sale as a SB Ford Mustang lower radiator hose spring. Hope this helped! Rod Wesling.