my car idles fine and temp stays low,,,,i put in gear she overheats and boils i just replaced the rad,new hoses and thermo

When transmission is placed into gear - it demands additional cooling from the system to maintain proper engine temperature - this also requires full volume from the water pump.. Sometimes a bore scope is helpful by viewing the h2o pump impeller through radiator hose nipple (hose removed from pump) it doesn’t take much pitting of the impeller to cause overheating problems .. Observe closely! This failure is not a common occurrence but it absolutely can and does happen - to any vehicle that utilizes a coolant / water pump. Considering the year model - this scenario is a very strong possibility. Good luck!