There are several different ways to search for questions in the GSS. One possibility is to go to the main codebook which includes the wordings of all GSS questions in the cumulative file. A second possibility is to go the questionnaire files and conduct a standard text search using regular search utilities. Be aware that such searches would only cover the particular version and year of the GSS that you were accessing. Also, note that while recent GSS questionnaires generally included GSS mnemonics, this is not the case for most questionnaires.
The GSS Data Explorer search function covers both mnemonics and question text for each variable in the cross-section data. Basic analysis of variables can also be conducted.
The Subject Index in the GSS Codebook is a useful resource to find various information about the GSS. When looking for specific question, be aware that between 2006 and 2014, it only covers questions asked in the cross-sections. Items asked only in the panel reinterviews were are not covered, including two ISSP modules.
There are two different resources available to locate variables in the panel reinterviews. The first is the Panel Codebook, which documents all questions and frequencies asked in the panel reinterviews, similar to the GSS Cumulative Codebook. The second is the Cross-Section and Panel Variable and Module Identification, which can be used to identify both the modules with which any given variable is associated, and which, if any, panel reinterviews the module appeared in.