Sour wine in stew

Welllll- it wouldn't hurt, but you could have a real problem here- Beef Bourguignon is, to a great extent about the wine, and wine flavors are quite complex;when they go off you're likely to have a complex problem that won't be simply resolved. If a little bitter (or sour- wine that's gone off is likely to develop acetic acid) is all you have to worry about some sweet (such as onion, more tomato, sweet peppers) might solve it, but you're likely to have to either start over or really mask the flavor with things like sherry, ancho chili powder, mustard- and you'll end up with a completely different dish. Of course it could be a great discovery, but the odds are poor.