my car is running rough

My car which is a 2007 chevrolet cobalt ls 2.2
motor was running rough I though my catalytic
converter was stopped up so I cut it out and put a
pipe where the catalytic converter was and every
since my car is doing a lot of crazy stuff smell gas
from my tail pipe its running rough at times no
power at time do I have to have a catalytic
converter on or does it cause problems on a cobalt  
if you don't have it on??