The Cushing Village development proposal has hit another wall. After the Planning Board said it likely won’t grant a special permit for a fourth story to be added to a building, the developer said he may withdraw his application for the project, according to Sami Baghdady, chairman of the Planning Board. Cushing Village would bring a mix of apartments and retail space to Common Street between Trapelo Road and Belmont Street. It has faced persistent opposition from residents concerned that it is too large for the neighborhood. Baghdady said in an e-mail that the developer will make a decision by the first week of August.