Ok so my car is chugging like its a train. It is a little sluggish and may be running a little rich. Almost wants to cut off at or near a dead stop and rumbles at speed with the faster the chugging. No SES lights or anything. I'm thinking maybe a spark plug or opti issue. Would a dead o2 sensor make the car run this bad?

 

It would, but probably not that badly. You are more than likely experiencing an opti malfunction. Good Luck

 

Yeah I'm about due for a $300 repair