Are you sitting high or low behind the kit?
What EvilDrummer said will probably work for you, try to play every hit as relaxed as possible.
Here's what you can try:
Sit behind your kit and take the snaredrum away for a bit. Set the metronome at +/- 100 bpm and start playing 16th notes RLRL. Now place your hands on the middle of your upper legs and feel if there is alot of tension there while playing. At relative low tempo's there should be some tension but not alot. When you feel that there is alot of tension actively try to relax those muscles while playing the 16 notes. When you relax the upper muscles you'll have to bring the power from your lower legs and ankles.
Also check out this video in around 2 minutes, Flo talkes about "dribbling" the pedal like a basketball. This is a great way to learn to use the rebound of the pedal against the drumhead.
Hope this helps and good luck!