I have an 84 monte Carlo ss with stock 305 . I drive it half of the year or anytime i get the chance. I love it . but this morning I hopped in and my throttle got stuck open because the spring was stuck . I shut it off repositioned the spring and restarted it. Everything was good. I get about a mile down the road and pop the hood and I have coolant boiling out of the overflow and no heat. Last year i replaced the blower motor and wheel and I never had good heat but none the less heat. Right now i think its the thermostat which i replaced last year with the motor and wheel. Could it be the heater core ? Does the coolant boiling over point to anything specific or is it just related to the thermostat . also what thermo should I put in ,160,180,190. Also I posted a pic of a sector gear that broke in the ignition. Does anyone have a part bumber . thanks in advance