Need to find out WHY the cat clogged..... have you had a look into your plenum yet? If it hasn't been dealt with yet, good bet that it's blown. Replacing the cat before you fix it will only ensure you get to replace the cat again....

 

My 96 was doing the same with the shifting a $900 dollar rebuild and it was still doing it I replaced $230 in sensors in the tranny pan and runs like a scolding dog now can stop it so that's somthing to look in to it wasn't throughing any codes for the sensors like it was suppose to so check in to it