Before revision:  An extensive simulation experiment shows potentially huge improvement in the bias and the MSE by using the CSA-2SLS  when instruments are correlated with each other and there exists large endogeneity .
After revision:  An extensive simulation experiment shows potentially huge improvement in the bias and the MSE by using the CSA-2SLS estimator outperforms the alternative estimators when instruments are correlated with each other and there exists large endogeneity .