The heater was blowing heat and all of the sudden it was blowing cold air and the etc light came on

Hello, air temperature from the climate control system and the throttle control warning light coming on does not really work together and seems to indicate two separate problems. First, ensure you have proper electrical power from a known good and fully charged battery and functioning charging system. Following this, the climate control system should be checked to determine why there is no hot air. Then, the throttle control and engine performance system should be checked to find out what's happening in that system. Use this link to find some shops near you that can help with your concern: www.repairpal.com/repair-shops