Did you just put a clutch in it? If so, they probably put a pansie clutch in it. IE: the wimpy $75 clutch that no one in their right mind would even put in a puddle-jumping Cavalier.
I had the clutch replaced in my Sonoma two winters ago because it was cold outside and I had no where to work. I had the half ton version and they still put the pansie clutch in it. It was so wimpy it'd slip with my 2.5L if I shifted hard in to second gear without completely dumping the clutch. I ended up smoking it in 3 weeks and they put a new one in for free (since they charged me 350 freaking dollars for a $75 clutch and 2 hour job I didn't feel guilty) due to their 1 month warranty. ****heads. I'll spare you my story about theft of certain items from my truck.
I think you're stuck with it unless you take it back and they put a real pressure plate in it. I remember when I got mine changed I just about killed the pedal. It used to be more difficult to press down than the brake pedal. After the clutch job it was easier to press down than the accelerator.