This is a very interesting post that proves how fluid a language can be. For me the only acceptable version is "if I am late, I will call you." Neither "will" nor "going to" can be used in if clauses. It may be because I've been an English teacher for years, and this has affected my English in making it (overly) standardized. However, putting overt future expression into if clauses is considered "wrong", with students even being scored lower on international tests for doing so.