At which point of the travel does it exactly happen? If you are talking about a small spring like feeling once the pedal is completely on the floor than this is normal. There is kick down switch at the bottom. Make sure that this switch is exposed thru the carpet. The carpet has an opening for the switch. I've seen many people put the carpet over it causing the pedal to feel very weird. Another thing that I have seen numerous times is the clip that anchors the pedal to the floor come completely off. This will also cause a weird feeling.
My suggestion is to take out the carpet check the anchoring of the pedal and switch operation. Reinstall carpet, paying attention to the opening in the carpet for the switch.

If this doesn't solve your problem you need to have your cable and linkage checked.

Vin