Here are some things you can try in order:
1. Remove the “P” trap from your sink drain pipe and clean it out.
2. Run liquid plumber or use a real plumber to clean your pipes. Clean pipes with good drainage will reduce/eliminate your system backing up out of the air gap faucet.
3. Use a longer length of tubing to the drain saddle and wrap the excess in loops around the drain pipe.
4. Unscrew the plastic nut from the drain saddle and poke out the opening to make sure it is clear and nothing is lodged in there.
5. Move the drain saddle to a point closer to the sink, however this might transfer the “gurguling noise” from the faucet to the sink drain. If you mount the drain saddle on a horizontal section of pipe you will need to put the hole at a downward angle so the waste water from your system falls into the drain pipe, otherwise you will definitely have water backing up out of your faucet.
6. Insert the 3/8” tubing a few inches inside the drain saddle so that it hits the opposite wall of the pipe, and then curves down. This usually cures sink drain noise, but in your case it might make your backing up problem worse.
Do items 1-4 first, and then check your system for problems again. If you still have problems then do 5 and/or 6.