thought the catylic coverter was the problem but the exhaust said he thinks it jump time what do you think?

on tuesday after work i clock out at the phone booth then got back in the car when it strated acting like it didn't want to go so i put in reverse then put it in drive and it went got home and a big cloud of white smoke was coming from the hood went and brought a catylic converter and the exhaust said it was't the problem so what is? in your opinion