Stochastic simulation following estimation command

[jpfeifer]

This seems to be numerical imprecision. You can see that iR is constant:

THEORETICAL MOMENTS
VARIABLE MEAN STD. DEV. VARIANCE
iR 0.0000 0.0000 0.0000

A general remark: your estimation results are wrong as you are not handling parameter dependence correctly. You can see that if you change

biglamda  = 1.02;     // balanced growth rate (new)

Then your steady state file will not work. See e.g.

Matrix must be positive definite with real diagonal

The two-sided HP-filter is not recommended. The biggest issue is that you are not handling parameter dependence correctly. Please read Pfeifer(2013): “A Guide to Specifying Observation Equations for the Estimation of DSGE Models”