Need Help With Integra!!!

I have a 1993 Acura Integra RS. I have a miss at idle in drive or reverse, but when I accelerate the miss goes away and the car drives fine at higher speeds. A mechanic told me that my catalitic converter was clogged and I was getting back preasure. Can this be possible?
Or what can it be?

can you describe the "miss" in more detail? if it goes away at higher speeds it might be a trans. problem

It feels like a thump thump thump...Then when I accelerate it rides fine at higher speed. It only happens when I am either in park or when I come to a stop.