I tried this
pkg load signal
[a,b,c,d] = tf2ss(q);
step(ss(a,b,c,d))
representing high order systems in transfer function form is not a good idea in general.
The pzmap of 'q' showed that the poles are all in the left half plane. That hinted that the coefficients are still probably good; which is why I tried converting to state space.
If possible in your application, avoid transfer functions where the order is very high.
Regards,