Need Help With Integra!!!

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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?

[WReX]

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

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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.