My first thought was Nami, to be honest.
Alistar is an interesting choice. I know you're looking for someone ranged, but he does have a targetted gap closer that I think would make you interested. His heal is also AOE, and it's a good pushing tool if you max it first. However, it's not as strong as Taric's or Sona's healing capability.
There are not a lot of champions with aura effects that give free stats like Taric. The only one coming to mind is Sona, and she also has a heal that you are looking for. Her harass and trading ability in lane are great, but she has by far some of the lowest base stats in the game. She is easy to bully.
Are you looking for a self heal or a targetted heal for your adc? If you're looking for a self heal, Maokai, Gragas, and Fiddlesticks are all uncommon, unorthodox supports that have worked in the past for me. You can always buy a Relic Shield to help sustain your adc, too! Fiddlesticks would fit your description easily if you are looking for a self heal, since he is ranged, has hard cc, and a self heal. Maokai and Gragas both have good cc and self heals as well, but they are melee.
The last two that I can think of are Kayle and Nidalee. They're both very uncommon supports, as well. However, they are both situational ranged/melee champions that have targetted heals, great harass, and good all ins. If I have to say which one supports more of a support role, I would say Kayle. He can make your adc invincible for a few seconds. I would say picking up Kayle is probably the better idea. She is great in every lane and with every role. Having a champion that you can fall back on like that is a great idea!
EDIT:
You can also sustain your adc through flat out blocking the damage and applying damage reduction. The best champions that I believe for doing this are Maokai, Braum, and Janna. Good luck!