Hello I need some help. a couple of days ago my exhaust fell off due to rust. so while trying to replace the exhaust I cut the oxygen tube leading to the cat. the car ran fine for a day or two not it wont even idle. when I can get it going it lags and sputters like it is coughing. Any help?

P>S> My car died a few eeks ago no power at all. after some trouble shooting it was found to be a burned fusible link on the starter under the car. just thought I would pass that on.