if only happens when brake applied....check brake booster hose and connection.your probably going to have to take to a shop that specializes in diagnostics.these codes will only set when fuel trims go above 25%.need a good scan tool to monitor short and long term fuel trim under various load conditions....that is just a start.why did mechanic clean injectors?did he do a injector drop test?shop did injector cleaning/smoke test?what did they say about diagnostic scan data info?