Over the last few Google search algorithm updates, exact match domains (EMD's) were devalued. This could be one of the reasons why you are not ranking as highly for the term "pizza codes" while the previous domain was.
The deranking (and domain change coincidentally) were right around that time. Interestingly, I rank higher for 'pizza codes' now, and a lot lower for terms like 'papa johns coupons'.
