  We study a number of different ingredients related to the $\theta$
dependence, metastable excited vacuum states and other related subjects using a
simplified version of QCD, the so-called "deformed QCD". This model is a weakly
coupled gauge theory, which however preserves all the relevant essential
elements allowing us to study hard and nontrivial features which are known to
be present in real strongly coupled QCD. Our main focus in this work is to test
the ideas related to the metastable vacuum states (which are known to be
present in strongly coupled QCD in large $N$ limit) in a theoretically
controllable manner using the "deformed QCD" as a toy model. We explicitly show
how the metastable states emerge in the system, why their life time is large,
and why these metastable states must be present in the system for the
self-consistency of the entire picture of the QCD vacuum. We also speculate on
possible relevance of the metastable vacuum states in explanation of the
violation of local $\cal{P}$ and $\cal{CP}$ symmetries in heavy ion collisions.
