. . . " the code they came up with was 430 I think - indicating a problem with the catalytic converter."
It is possible that it was P0430 - Catalyst System Efficiency Below Threshold (Bank 2)
Much money is spent by car owners replacing catalytic converters to solve problems of this nature only to find the new catalytic converter hasn’t solved the original cause of the problem.
Your 430 code (P0430) could mean the converter is toast, but not necessarily. As has been pointed out, more diagnosis is wise. Faulty 02 sensors and exhaust leaks are just a couple of things that can trigger this DTC.
CSA