2002 S80 Replaced Catalytic Converter

[gman656]

I recently replaced my catalytic converter on a 2002 S80 with 140k miles. Prior to replacement I had occasional severe loss of power and engine stalled out. Runs real smooth now, but I am not getting a strong acceleration at start or at highway speed.... seems somewhat sluggish. Any thoughts? I have a great Volvo mechanic, but the cost of repairs is starting to wear me out.... the mass airflow sensor was replaced about 6 months ago as well.
Thanks for any advice
George