Volkswagen Repair: Jetta sputtering...., exhaust pipe, catalytic converter

Question
My car was driving just fine until I was about 40 miles from home, and I was driving on the freeway about 70 mph, and all of a sudden it drops down to 25 mph, and the car starts sputtering. I was able to luckly get it off the freeway to the next exit where I could only drive the car no more than 10 mph or it would start sputtering.The mechanic that AAA sent out to look at before the tow truck came, thought it might be the catalyic convertor. Any ideas on what it might be?

Answer
Trista,
  I am not familiar with your vehicle...however, if it is a plugged catalytic converter, the vehicle would be able to start after several minutes of the engine dying, as the converters are rarely fully plugged and the back pressure of the exhaust system will slowly bleed through.  The next time the vehicle experiences this problem, try to place your ear near the exhaust pipe (at the rear of the vehicle), and listen for a hiss...the pipe will be warm/hot, so be careful.  Hope this helps.  Jerry