1999 Jetta 2.0 4-cyl: Poor power and acceleration, is this car a lemon?

[Dano2]

Hi,
We bought a 99 Jetta, 4 cylinder 2.O engine about 1 1/2 years ago. It has been an ok car and the gas mileage is good.
However it is gutless and has a hard time getting up to speed. We recently had it tuned and it failed emmisions so we had a new catalytic converter.
It still runs the same, slow at getting going.
My questions: is this car a lemon? and is there anything we can do to get a little more power out of the engine? It is my wifes car and she really likes it, it drives nice and runs good just sluggish...
thanks for you time...