Answer: I apologize for the delay in answering your question. If it is really crab grass, it is an annual weed and will die out over the winter; it would not be able to come up through mulch. Based on your description, I think it is probably some other kind of difficult-to-control perennial grass. I would suggest you work with your state cooperative extension service to indentify the grass and determine the best approach to controlling it. They should also be able to help you develop a custom lawn care plan to reinvigorate your overall lawn. Here is their web site and contact information.
Good luck with your lawn!
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