Does shifting my 3 speed automatic into nuetral when coasting to a traffic light save me gas?

I have a 2003 Chevy Cavalier with the 3 speed automatic - pitiful, I know. Recently, I started shifting the auto into neutral while approaching traffic lights and on long downhill sections of road under the umption that I would be saving gas while driving at low RPMs. I then read that some slush-box cars automatically go into a "neutral" mode under coasting conditions without actually being put into neutral due to programming in their main ECUs. I'm uming that my car does not have that programming so I'm wondering if my technique is actually worth it. I'm not worried about my transmission as it has proven bullet proof and I always rev match before shifting back to Drive on the rare occasion that I'm not at a stop beforehand.