The leak is inbetween the cap and the injector

 

Bad Injector. I had a simlar problem. Apparently, it is not uncommon for FD injectors to leak at the top where the plastic meets the metal injector body. Or you could just need some new $0.50 O-rings. Good luck with that. It's a PITA to even get to the injectors.

 

How do I know if its the o rings?

 

Those orings are nowhere near $0.50 ea. From Mazda they are $5-8 each, and each injector has two.

Anyway, a pair of used, cleaned injectors is about $100.

Dave

 

If you are lucky they are the o-rings but the only way is to actually get them cleaned and calibrated to be sure, but even then you still have to put them back in the car and test them out.
This happened to me and ended up being the actual injectors themselves.

Try www.rceng.com they will clean and calibrate for cheap