Q: I don't think my car is transferring the antifreeze properly through the radiator or the engine.

Ok my car's fluid warning light started blinking when I started to stop and once I stopped it stayed on a more solid but after I accelerate it goes away again then the cycle repeats. It had been time to change my thermostat because it was stuck open so my temperature gauge was always cold and last week the temperature went up to the normal range and I saw steam coming from the coolant reservoir so I changed the thermostat and nothing changed. It still doesn't run hot, it goes to the normal level but I still can see the steam or smoke coming from under the hood once I stop for a while. And there is this part in front of the radiator that is hanging and it looks like some kind of sensor and it's right above this canister looking part right behind the grille on the left side. So I don't know if that has anything to do with my problem. Thanks.

My car has 253000 miles.
My car has an automatic transmission.