My check engine light came on and the 97 4 cyl. Grand Am was acting funny. Shaking and loss of power. The test ran said bad O2 sensor. Replaced O2 sensor and the light went off but the car is still acting funny and has even died 3 or 4 times. It is hesitant on shifting (automatic) and still shakes while in idle and going down the highway. Is it the cat converter and what is the cheapest place to get a new one? Appreciate anyone's help.

Hi. I had a lot of problems w my 2001 GA SE. Loss of power etc. Ok first I had the Cat replaced. Good idea and my car ran better. Then I changed my spark plugs and those black boots that cover the plugs. Now my car runs like new :iceslolan

Good luck!

Did you replace both sensors? -theres one before and one after the cat.