Many sauces include vinegar in them. Whether it is too much is going to be a personal opinion. Sweetness in the form of honey or brown sugar is often used to off-set some of the acidity.
Drink more beer
Add lemon juice or white vinegar. :-)
It's basically a blend of mayonnaise and barbecue sauce. Likely a little bit of ketchup, too.
apple cider vinegar
Mixing soy sauce with vinegar will thin the soy sauce, and give the sauce a strong vinegary flavour, (depending on the amount of vinegar used).
No, vinegar is not toxic, you may be sick if you taste too much at once but it will not harm you, vinegar is used in many foods such as pickled onions, beetroot, cabbage etc, it is in tomato sauce, mayonnaise, brown sauce and many other similar sauces its even dribbled on food such as Fish and Chips to enhance the flavour.
Baking Soda is used to neutralize the acidity of the tomatoes in spaghetti sauce. If there was too much baking soda added, you might be able to add a little vinegar or even better a red wine vinegar to raise the acidity of the sauce or add more tomato sauce.
Add a little acidity to it. Lemon, vinegar, tartar, or alum, depending on the sauce can remove some sweetness. Salt accentuates sweetness.
Well, that's pretty much the point of soaking it. Maybe you could try a different vinegar. Let me recommend using either malt or balsamic vinegar in your marinade. Cut back on the amount of vinegar and add more Worcestershire sauce. A little more molasses might help, too.
Raw peeled potato will draw sweetness from the sauce
Perhaps you did use too much vinegar. If the recipe called for cider vinegar it has a much stronger smell and flavor than white vinegar and you want to try making another batch using white vinegar.
No such thing!