If you are going to give up on the starter, I wouldn't add yeast to it as I think this will be the worst of all worlds.
Just start a really slow poolish from scratch. Even if some consider this in some way lessor than sourdough, it's just an opinion I disagree with. You'll get some lovely bread that is completely hassle free and better than pretty much anything you're likely to have tasted before.
I'm going to give the sourdough a bit more chance. I've noticed it gets a skin of dried flour on top after several hours. This morning, I removed the skin and there were several bubbles just underneath. So something is happening.
Question: what consistency should the starter be? I think mine was a little too dry before. I now have it much wetter - almost like pancake batter.
The Joy of Cooking says to toss the starter and start over if no real activity within three days. It's been about six for me. Should I start over? If I do, I'm just going to make a poolish.