TIF - please let us know what your surgeon says.
I did not have TIF, I had regular fundo, and also have a sour taste (which I had before surgery too, and was apparently associated with reflux). I believe the sour taste is "water brash". There are several people who report having the sour taste after their fundoplications, even if they didn't have it before. I think it may be caused by the surgery, irritating and inflaming the esophagus which prompts the body to create an alkaline solution to wash the irritant away via swallowing.
The sour taste I'm having seems to be decreasing week to week (I am 5 weeks out), and I've read in other cases it goes away. I'm thinking mine will go away too.
In the case of TIF, the esophagus may be irritated from the surgery and is doing the same defense mechanism of prompting the body to create that fluid. Maybe the reason it's sour is so that we swallow it, i.e. we do not want to keep that bad tasting stuff in our mouth so we swallow, which could be what the esophagus "wants" since it's irritated. It does not know that the irritation is from surgery and not reflux.
Anyways, please let us know what the doctor says about it.