Check engine light, major hesitation

Hi,
My car is a 2000 Toyota Celica; approx. 114, 500 miles; 1.8L engine. My check engine light has been on for about a year. When I had it diagnosed, they told me that the problem was a catalytic converter and that it would cost close to $2000 to repair. But the car was running fine so I opted to wait. The car DID pass smog in CA shortly after this.

However, in the past few months the car is hesitating. When the gas pedal is depressed, the engine revs but nothing happens for a few seconds. Sometimes I actually have to pump the gas pedal to get the car to go. Is this related to the catalytic converter, or is this another problem? Should a catalytic converter repair cost as much as I was quoted?

Thanks for your help.