I would add my support to the idea you are either in ketosis or not eating enough to fuel your body. I had these symptoms relatively frequently when I was struggling with anorexia and getting too little calories and too few carbs. I think DeanS is right that as a male, teen and an athlete restricting and IF might be more stress than your body needs at this stage. But I could be mistaken and everyone has to go with what feels right to them. Perhaps experiment with upping the food for a little bit or giving the IF a break to see how that effects the salivating.

Ok. So you're a teenage, male athlete. IMHO restricting your carbohydrate to such low levels should not be necessary even if you just lay around all day. It is more important that your carbohydrate comes from healthy sources and I would guess that you are doing that already. Obviously, you are the best judge of what what works for you. That also means that it is always a good idea to use some healthy skepticism when you read advice or information on a blog or on Paleohax ;-).

The only time I've experienced excess salivating with a metallic taste in my mouth is when I had not eaten enough. I was probably in ketosis when this happened, though this was not intentional.

i would suspect a neurotoxin ingestion. Just google neurotoxin, metallic taste and read for a lifetime about it.